fix(apigee): retry "the resource is locked by another operation"

[alec-pinson]

Apigee serialises long-running operations per organization. A mutation issued while another operation is in flight against the same org is rejected immediately with HTTP 400 the resource is locked by another operation rather than being queued.

google_apigee_instance already retries this via transport_tpg.IsApigeeRetryableError (added for hashicorp/terraform-provider-google#10979), but every other org-scoped asynchronous Apigee resource can hit the same error and does not.

This is easy to reproduce with a for_each that creates two of them concurrently in a single apply — the first succeeds, the second fails outright:

google_apigee_endpoint_attachment.this["euw2"]: Creation complete after 1m5s
Error: Error creating EndpointAttachment: googleapi: Error 400: the resource is
locked by another operation where endpoint attachment swp-euw2 is currently being
created for organization <org> by operation: 1c83301f-195f-4d20-b6f4-7d5c8f6b66e8

There is no practical config-side workaround: Terraform builds dependency edges at the config-node level rather than per instance, so neither a time_sleep stagger nor a child-module-per-item stagger serialises a dynamic for_each — every instance still starts after the longest sleep. That leaves -parallelism=1 for the whole apply, which also serialises the 30–45 minute google_apigee_instance creates.

This PR applies the existing predicate to the remaining org-scoped async Apigee resources: EndpointAttachment, InstanceAttachment, EnvgroupAttachment, Environment, Envgroup and NatAddress.

Note that InstanceAttachment already carries mutex: apigeeInstanceAttachments. That mutex only covers a single provider process and does not prevent collisions against the same org from a different resource type, so the predicate is complementary rather than redundant.

Contributes to hashicorp/terraform-provider-google#12369, hashicorp/terraform-provider-google#11445 and hashicorp/terraform-provider-google#10084.

apigee: fixed an issue where concurrently creating `google_apigee_endpoint_attachment`, `google_apigee_instance_attachment`, `google_apigee_envgroup_attachment`, `google_apigee_environment`, `google_apigee_envgroup` or `google_apigee_nat_address` resources could fail with a 400 error stating the resource is locked by another operation

[github-actions]

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