gcs-data-bucket metadata key is now modifiable by the user

[bcreddy-gcp]

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workbench : Made `gcs-data-bucket` metadata key modifiable. 

[github-actions]

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[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

google provider: Diff ( 1 file changed, 1 deletion(-))
google-beta provider: Diff ( 1 file changed, 1 deletion(-))
terraform-google-conversion: Diff ( 1 file changed, 1 deletion(-))

[modular-magician]

Tests analytics

Total tests: 21
Passed tests: 21
Skipped tests: 0
Affected tests: 0

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• workbench

🟢 All tests passed!

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[github-actions]

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[roaks3]

I can't quite tell if this is a breaking change, per https://googlecloudplatform.github.io/magic-modules/breaking-changes/breaking-changes/#field-level-breaking-changes. Do you know what happens if a user has this field specified right now, and then upgrades the provider? It seems like it could produce a new change that could be unexpected. Might be worth a test as well to demonstrate what happens.

[bcreddy-gcp]

This key was never allowed to be set by terraform nor was set by the backend. We now allow instances to have it set by Terraform update. Also newer instances can be created with the said key on Terraform.

[roaks3]

I was more considering if they had the key currently in their config, even though it is ignored:

    metadata = {
      gcs-data-bucket = "some-value"
    }

I believe someone could be using this config today, and then with this change, it would suddenly apply the "some-value".

But assuming that's correct, this does seem like fairly unusual usage, and I expect we would be fine including it in a minor version. I also see that there is precedent (we removed nvidia-driver-gcs-path in #10900).