Container_cluster: enables GKE workload metrics

[geojaz]

As per https://cloud.google.com/blog/products/operations/managed-metric-collection-for-google-kubernetes-engine
GKE workload metrics are available in beta.

This updates the schema so that WORKLOAD is an allowed value for monitoring_config

This fixes hashicorp/terraform-provider-google#10275

If this PR is for Terraform, I acknowledge that I have:

• Searched through the issue tracker for an open issue that this either resolves or contributes to, commented on it to claim it, and written "fixes {url}" or "part of {url}" in this PR description. If there were no relevant open issues, I opened one and commented that I would like to work on it (not necessary for very small changes).
• Generated Terraform, and ran make test and make lint to ensure it passes unit and linter tests.
• Ensured that all new fields I added that can be set by a user appear in at least one example (for generated resources) or third_party test (for handwritten resources or update tests).
• Ran relevant acceptance tests (If the acceptance tests do not yet pass or you are unable to run them, please let your reviewer know).
• Read the Release Notes Guide before writing my release note below.

Release Note Template for Downstream PRs (will be copied)

container_cluster: Updated `monitoring_config` to accept `WORKLOAD`

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review.

Thanks for your contribution! A human will be with you soon.

@c2thorn, please review this PR or find an appropriate assignee.

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 2 insertions(+), 2 deletions(-))
Terraform Beta: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))

[geojaz]

Hrm, I guess this should be beta only. I'll fix that

[modular-magician]

Hello! I am a robot who works on Magic Modules PRs.

I have detected that you are a community contributor, so your PR will be assigned to someone with a commit-bit on this repo for initial review.

Thanks for your contribution! A human will be with you soon.

@ScottSuarez, please review this PR or find an appropriate assignee.

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 2 insertions(+), 2 deletions(-))
Terraform Beta: Diff ( 2 files changed, 4 insertions(+), 4 deletions(-))

[geojaz]

I was able to tweak the generated files for beta/ga, but couldn't figure out how to gate the docs. If someone could point me towards that, I will fix it.

[c2thorn]

@geojaz doc files themselves are not versioned, we just notate a beta-only field with a simple [Beta] tag. There should be examples of this in that doc file

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 2 insertions(+), 2 deletions(-))
Terraform Beta: Diff ( 3 files changed, 5 insertions(+), 5 deletions(-))

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 1 insertion(+), 2 deletions(-))
Terraform Beta: Diff ( 3 files changed, 4 insertions(+), 5 deletions(-))

[c2thorn]

/gcbrun

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 1 file changed, 1 insertion(+), 2 deletions(-))
Terraform Beta: Diff ( 3 files changed, 4 insertions(+), 5 deletions(-))

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccDatasourceGoogleServiceNetworkingPeeredDnsDomain_basic|TestAccComputeRouterPeer_advertiseMode You can view the result here: https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=210243

[geojaz]

I'm unable to see the failure, if someone will let me know what needs to be fixed, i'll give it a shot.