r/rds_cluster: add ability to promotion read replica cluster to standalone

[johnsonaj]

Description

Removing replication_source_identifier now promotes a read replica cluster to standalone

Relations

Closes #31320

References

Output from Acceptance Testing

% make testacc TESTARGS='-run=TestAccRDSCluster_' PKG=rds

make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.23.3 test ./internal/service/rds/... -v -count 1 -parallel 20  -run=TestAccRDSCluster_ -timeout 360m
2024/11/27 13:17:11 Initializing Terraform AWS Provider...
    cluster_test.go:2193: serverless does not support snapshot restore on an empty volume
--- SKIP: TestAccRDSCluster_SnapshotIdentifierEngineMode_serverless (0.00s)
--- PASS: TestAccRDSCluster_availabilityZones (109.93s)
--- PASS: TestAccRDSCluster_localWriteForwarding (112.26s)
--- PASS: TestAccRDSCluster_basic (121.95s)
--- PASS: TestAccRDSCluster_deletionProtection (157.59s)
--- PASS: TestAccRDSCluster_storageTypeAuroraIopt1UpdateAurora (158.88s)
--- PASS: TestAccRDSCluster_storageTypeAuroraUpdateAuroraIopt1 (169.40s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_preferredBackupWindow (307.98s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_kmsKeyID (339.00s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_encryptedRestore (339.13s)
--- PASS: TestAccRDSCluster_SnapshotIdentifierEngineMode_provisioned (349.28s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_masterUsername (350.29s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_deletionProtection (367.78s)
--- PASS: TestAccRDSCluster_SnapshotIdentifierVPCSecurityGroupIDs_tags (264.57s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_masterPassword (312.41s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_tags (262.58s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_vpcSecurityGroupIDs (334.52s)
--- PASS: TestAccRDSCluster_serverlessV2ScalingConfiguration (174.12s)
--- PASS: TestAccRDSCluster_ManagedMasterPassword_managedSpecificKMSKey (111.74s)
--- PASS: TestAccRDSCluster_ManagedMasterPassword_managed (96.29s)
--- PASS: TestAccRDSCluster_ManagedMasterPassword_convertToManaged (144.63s)
--- PASS: TestAccRDSCluster_port (151.42s)
--- PASS: TestAccRDSCluster_Scaling_defaultMinCapacity (255.00s)
--- PASS: TestAccRDSCluster_SnapshotIdentifier_preferredMaintenanceWindow (303.13s)
--- PASS: TestAccRDSCluster_scaling (262.88s)
--- PASS: TestAccRDSCluster_identifierPrefix (115.67s)
--- PASS: TestAccRDSCluster_snapshotIdentifier (342.23s)
--- PASS: TestAccRDSCluster_tags (122.74s)
--- PASS: TestAccRDSCluster_backupsUpdate (151.99s)
--- PASS: TestAccRDSCluster_copyTagsToSnapshot (190.15s)
--- PASS: TestAccRDSCluster_engineLifecycleSupport_disabled (116.45s)
--- PASS: TestAccRDSCluster_SnapshotIdentifierEngineVersion_different (285.81s)
--- PASS: TestAccRDSCluster_minorVersion (839.18s)
--- PASS: TestAccRDSCluster_onlyMajorVersion (850.90s)
--- PASS: TestAccRDSCluster_NoDeleteAutomatedBackups (243.31s)
--- PASS: TestAccRDSCluster_allowMajorVersionUpgradeNoApplyImmediately (904.96s)
--- PASS: TestAccRDSCluster_storageTypeAuroraIopt1 (104.44s)
--- PASS: TestAccRDSCluster_storageTypeAuroraReturnsBlank (103.44s)
--- PASS: TestAccRDSCluster_identifierGenerated (116.06s)
--- PASS: TestAccRDSCluster_disappears (103.33s)
--- PASS: TestAccRDSCluster_copyTagsToSnapshot_restorePointInTime (326.80s)
--- PASS: TestAccRDSCluster_GlobalClusterIdentifierEngineModeGlobal_add (109.46s)
--- PASS: TestAccRDSCluster_SnapshotIdentifierEngineVersion_equal (320.35s)
--- PASS: TestAccRDSCluster_GlobalClusterIdentifierEngineMode_global (187.14s)
--- PASS: TestAccRDSCluster_PointInTimeRestore_enabledCloudWatchLogsExports (264.32s)
--- PASS: TestAccRDSCluster_allocatedStorage (1430.12s)
--- PASS: TestAccRDSCluster_performanceInsightsRetentionPeriod (1524.64s)
--- PASS: TestAccRDSCluster_EnabledCloudWatchLogsExports_mySQL (180.55s)
--- PASS: TestAccRDSCluster_GlobalClusterIdentifierEngineMode_provisioned (201.78s)
--- PASS: TestAccRDSCluster_missingUserNameCausesError (4.94s)
--- PASS: TestAccRDSCluster_iops (1642.86s)
--- PASS: TestAccRDSCluster_GlobalClusterIdentifierEngineModeGlobal_update (191.51s)
--- PASS: TestAccRDSCluster_pointInTimeRestore (253.52s)
--- PASS: TestAccRDSCluster_storageTypeGeneralPurposeToProvisionedIOPS (1059.69s)
--- PASS: TestAccRDSCluster_allowMajorVersionUpgrade (1829.40s)
--- PASS: TestAccRDSCluster_takeFinalSnapshot (204.80s)
--- PASS: TestAccRDSCluster_pointInTimeRestoreViaResourceID (264.03s)
--- PASS: TestAccRDSCluster_enableHTTPEndpointProvisioned (190.98s)
--- PASS: TestAccRDSCluster_iamAuth (92.96s)
--- PASS: TestAccRDSCluster_kmsKey (118.95s)
--- PASS: TestAccRDSCluster_password (171.86s)
--- PASS: TestAccRDSCluster_dbSubnetGroupName (110.17s)
--- PASS: TestAccRDSCluster_encrypted (112.99s)
--- PASS: TestAccRDSCluster_updateIAMRoles (114.11s)
--- PASS: TestAccRDSCluster_performanceInsightsKMSKeyID (1489.37s)
--- PASS: TestAccRDSCluster_networkType (209.26s)
--- PASS: TestAccRDSCluster_performanceInsightsEnabled (1515.71s)
--- PASS: TestAccRDSCluster_enableHTTPEndpoint (292.22s)
--- PASS: TestAccRDSCluster_allowMajorVersionUpgradeWithCustomParametersApplyImm (2066.91s)
--- PASS: TestAccRDSCluster_allowMajorVersionUpgradeWithCustomParameters (2129.88s)
--- PASS: TestAccRDSCluster_backtrackWindow (141.54s)
--- PASS: TestAccRDSCluster_engineVersionWithPrimaryInstance (1231.25s)
--- PASS: TestAccRDSCluster_engineMode (345.52s)
--- PASS: TestAccRDSCluster_engineVersion (424.57s)
--- PASS: TestAccRDSCluster_availabilityZones_caCertificateIdentifier (1573.87s)
--- PASS: TestAccRDSCluster_storageTypeIo1 (1540.78s)
--- PASS: TestAccRDSCluster_ReplicationSourceIdentifier_kmsKeyID (1962.57s)
--- PASS: TestAccRDSCluster_GlobalClusterIdentifierEngineModeGlobal_remove (196.50s)
--- PASS: TestAccRDSCluster_ReplicationSourceIdentifier_promote (2113.86s)
--- PASS: TestAccRDSCluster_domain (1780.46s)
--- PASS: TestAccRDSCluster_GlobalClusterIdentifier_replicationSourceIdentifier (2895.23s)
--- PASS: TestAccRDSCluster_storageTypeIo2 (1590.40s)
--- PASS: TestAccRDSCluster_dbClusterInstanceClass (3733.64s)
--- PASS: TestAccRDSCluster_GlobalClusterIdentifier_secondaryClustersWriteForwarding (3225.02s)
--- PASS: TestAccRDSCluster_EnabledCloudWatchLogsExports_postgresql (1840.55s)
--- PASS: TestAccRDSCluster_GlobalClusterIdentifier_primarySecondaryClusters (3012.71s)
PASS
ok 		github.com/hashicorp/terraform-provider-aws/internal/service/rds	4178.987s

[github-actions]

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[gdavison]

This new behaviour should be documented.

Also, should replication_source_identifier be ForceNew if it's changed to a different value? If so, consider a separate PR

[github-actions]

This functionality has been released in v5.79.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!