remove maxitems limit on appmesh_virtual_node backends

[nwsparks]

Description

Via AWS support it is possible to raise the quota on backends. This PR removes the Terraform side of the limitation. The AWS API will still return an error if you try to apply with more backends than the quota allows.

I'm not sure whether to classify this as a bug or enhancement? Leaning towards bug.

Relations

Closes #34658

Output from Acceptance Testing

Just running the virtual node tests, commented out the others as I wasn't able to get them to execute in a reasonable time or otherwise figure out how to limit this to the virtual node tests only.

make testacc PKG=appmesh
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/appmesh/... -v -count 1 -parallel 20   -timeout 360m
=== RUN   TestAccAppMesh_serial
=== PAUSE TestAccAppMesh_serial
=== RUN   TestVirtualNodeMigrateState
=== PAUSE TestVirtualNodeMigrateState
=== RUN   TestVirtualRouterMigrateState
=== PAUSE TestVirtualRouterMigrateState
=== CONT  TestAccAppMesh_serial
=== RUN   TestAccAppMesh_serial/VirtualNode
=== RUN   TestAccAppMesh_serial/VirtualNode/backendClientPolicyFile
=== CONT  TestVirtualRouterMigrateState
--- PASS: TestVirtualRouterMigrateState (0.00s)
=== CONT  TestVirtualNodeMigrateState
--- PASS: TestVirtualNodeMigrateState (0.00s)
=== RUN   TestAccAppMesh_serial/VirtualNode/backendDefaultsCertificate
=== RUN   TestAccAppMesh_serial/VirtualNode/listenerHealthChecks
=== RUN   TestAccAppMesh_serial/VirtualNode/dataSourceBasic
=== RUN   TestAccAppMesh_serial/VirtualNode/disappears
=== RUN   TestAccAppMesh_serial/VirtualNode/listenerTimeout
=== RUN   TestAccAppMesh_serial/VirtualNode/listenerValidation
=== RUN   TestAccAppMesh_serial/VirtualNode/tags
=== RUN   TestAccAppMesh_serial/VirtualNode/backendDefaults
=== RUN   TestAccAppMesh_serial/VirtualNode/listenerOutlierDetection
=== RUN   TestAccAppMesh_serial/VirtualNode/multiListenerValidation
=== RUN   TestAccAppMesh_serial/VirtualNode/logging
=== RUN   TestAccAppMesh_serial/VirtualNode/basic
=== RUN   TestAccAppMesh_serial/VirtualNode/backendClientPolicyAcm
=== RUN   TestAccAppMesh_serial/VirtualNode/cloudMapServiceDiscovery
=== RUN   TestAccAppMesh_serial/VirtualNode/listenerConnectionPool
=== RUN   TestAccAppMesh_serial/VirtualNode/listenerTls
--- PASS: TestAccAppMesh_serial (1596.35s)
    --- PASS: TestAccAppMesh_serial/VirtualNode (1596.35s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/backendClientPolicyFile (80.35s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/backendDefaultsCertificate (47.34s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/listenerHealthChecks (80.95s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/dataSourceBasic (71.97s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/disappears (45.41s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/listenerTimeout (75.83s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/listenerValidation (77.18s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/tags (105.47s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/backendDefaults (76.29s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/listenerOutlierDetection (76.34s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/multiListenerValidation (77.10s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/logging (106.64s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/basic (46.28s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/backendClientPolicyAcm (155.20s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/cloudMapServiceDiscovery (193.65s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/listenerConnectionPool (76.06s)
        --- PASS: TestAccAppMesh_serial/VirtualNode/listenerTls (204.27s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/appmesh    1596.451s
...

[github-actions]

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[github-actions]

Welcome @nwsparks 👋

It looks like this is your first Pull Request submission to the Terraform AWS Provider! If you haven’t already done so please make sure you have checked out our CONTRIBUTOR guide and FAQ to make sure your contribution is adhering to best practice and has all the necessary elements in place for a successful approval.

Also take a look at our FAQ which details how we prioritize Pull Requests for inclusion.

Thanks again, and welcome to the community! 😃

[ewbankkit]

LGTM 🚀.

[ewbankkit]

@nwsparks Thanks for the contribution 🎉 👏.

[github-actions]

This functionality has been released in v5.31.0 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!

[github-actions]

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If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.