Allow empty permissions_boundary attribute on aws_iam_user

[mgarstecki]

Fixes #5858

Changes proposed in this pull request:

• Allow empty permissions_boundary attribute for aws_iam_user, and treat it as an absent value.
• Add testAccCheckAWSUserPermissionsBoundary in aws_iam_user acceptance tests to check the value of the attribute on the AWS side.

Output from acceptance testing:

$ make testacc TESTARGS="-run TestAccAWSUser"
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./... -v -run TestAccAWSUser -timeout 120m
?   	github.com/terraform-providers/terraform-provider-aws	[no test files]
=== RUN   TestAccAWSUser_importBasic
--- PASS: TestAccAWSUser_importBasic (23.48s)
=== RUN   TestAccAWSUserGroupMembership_basic
--- PASS: TestAccAWSUserGroupMembership_basic (107.94s)
=== RUN   TestAccAWSUserLoginProfile_basic
--- PASS: TestAccAWSUserLoginProfile_basic (42.09s)
=== RUN   TestAccAWSUserLoginProfile_keybase
--- PASS: TestAccAWSUserLoginProfile_keybase (31.77s)
=== RUN   TestAccAWSUserLoginProfile_keybaseDoesntExist
--- PASS: TestAccAWSUserLoginProfile_keybaseDoesntExist (24.00s)
=== RUN   TestAccAWSUserLoginProfile_notAKey
--- PASS: TestAccAWSUserLoginProfile_notAKey (23.79s)
=== RUN   TestAccAWSUserLoginProfile_PasswordLength
--- PASS: TestAccAWSUserLoginProfile_PasswordLength (33.17s)
=== RUN   TestAccAWSUserPolicyAttachment_basic
--- PASS: TestAccAWSUserPolicyAttachment_basic (47.15s)
=== RUN   TestAccAWSUserSSHKey_basic
--- PASS: TestAccAWSUserSSHKey_basic (25.76s)
=== RUN   TestAccAWSUserSSHKey_pemEncoding
--- PASS: TestAccAWSUserSSHKey_pemEncoding (25.44s)
=== RUN   TestAccAWSUser_basic
--- PASS: TestAccAWSUser_basic (36.87s)
=== RUN   TestAccAWSUser_disappears
--- PASS: TestAccAWSUser_disappears (14.90s)
=== RUN   TestAccAWSUser_nameChange
--- PASS: TestAccAWSUser_nameChange (35.99s)
=== RUN   TestAccAWSUser_pathChange
--- PASS: TestAccAWSUser_pathChange (36.32s)
=== RUN   TestAccAWSUser_permissionsBoundary
--- PASS: TestAccAWSUser_permissionsBoundary (83.51s)
PASS
ok  	github.com/terraform-providers/terraform-provider-aws/aws	592.197s

[bflad]

LGTM, thanks @mgarstecki! 🚀

6 tests passed (all tests)
--- PASS: TestAccAWSUser_disappears (4.81s)
--- PASS: TestAccAWSUser_importBasic (7.01s)
--- PASS: TestAccAWSUser_pathChange (10.74s)
--- PASS: TestAccAWSUser_nameChange (10.88s)
--- PASS: TestAccAWSUser_basic (11.08s)
--- PASS: TestAccAWSUser_permissionsBoundary (27.91s)

[bflad]

This has been released in version 1.36.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!