google_vpc_access_connector missing GA args

[modular-magician]

Closes #11934

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Release Note Template for Downstream PRs (will be copied)

vpcaccess - promoted `machine_type`, `min_instances`, `max_instances`, and `subnet` in `google_vpc_access_connector` to GA

Derived from GoogleCloudPlatform/magic-modules#6718

[github-actions]

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