azurerm_machine_learning_workspace - Fix Key Vault ID validation error

[xuzhang3]

1. Fix ID validation error. The Key Vault ID returned by service is case insensitive.
2. Fix AccTest failure.

=== RUN   TestAccMachineLearningWorkspace_requiresImport
=== PAUSE TestAccMachineLearningWorkspace_requiresImport
=== CONT  TestAccMachineLearningWorkspace_requiresImport
--- PASS: TestAccMachineLearningWorkspace_requiresImport (689.67s)
PASS
ok      github.com/hashicorp/terraform-provider-azurerm/internal/services/machinelearning       706.525s

=== RUN   TestAccMachineLearningWorkspaceDataSource_basic
=== PAUSE TestAccMachineLearningWorkspaceDataSource_basic
=== CONT  TestAccMachineLearningWorkspaceDataSource_basic
--- PASS: TestAccMachineLearningWorkspaceDataSource_basic (1993.35s)
PASS
ok      github.com/hashicorp/terraform-provider-azurerm/internal/services/machinelearning       2023.477s

=== RUN   TestAccMachineLearningWorkspace_complete
=== PAUSE TestAccMachineLearningWorkspace_complete
=== RUN   TestAccMachineLearningWorkspace_completeUpdate
=== PAUSE TestAccMachineLearningWorkspace_completeUpdate
=== CONT  TestAccMachineLearningWorkspace_complete
=== CONT  TestAccMachineLearningWorkspace_completeUpdate
--- PASS: TestAccMachineLearningWorkspace_complete (1886.00s)
--- PASS: TestAccMachineLearningWorkspace_completeUpdate (2078.67s)
PASS
ok      github.com/hashicorp/terraform-provider-azurerm/internal/services/machinelearning       2084.885s

[stephybun]

Thanks @xuzhang3 LGTM 🍕

[github-actions]

This functionality has been released in v3.56.0 of the Terraform 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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