Deprecate container cluster fields

[c2thorn]

Part of hashicorp/terraform-provider-google#7185, hashicorp/terraform-provider-google#8032

Release Note Template for Downstream PRs (will be copied)

container: deprecated the following `google_container_cluster` fields: `instance_group_urls` and `master_auth` 

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 2 files changed, 173 insertions(+), 136 deletions(-))
Terraform Beta: Diff ( 3 files changed, 206 insertions(+), 178 deletions(-))

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 2 files changed, 35 insertions(+), 6 deletions(-))
Terraform Beta: Diff ( 2 files changed, 35 insertions(+), 6 deletions(-))

[rileykarson]

I don't think we should move forward with this deprecation. I know it's deprecated in the API, but the impact is going to be extremely large as many (probably most) users use this to set a node count on their default node pool prior to removal. For a change of this scope we would need a much more in-depth upgrade guide, and a better understanding of the impact.

Particularly, this field is ForceNew and the risk of users accidentally deleting their clusters is fairly high.

[rileykarson]

Same w/ initial_node_count (although less extreme), I don't feel great about moving old GKE fields without much more detailed guidance on how to move and understanding of user impact.

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccComputeForwardingRule_update|TestAccContainerNodePool_withGPU|TestAccSqlUser_postgresIAM You can view the result here: https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=211448

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 2 files changed, 23 insertions(+), 6 deletions(-))
Terraform Beta: Diff ( 2 files changed, 23 insertions(+), 6 deletions(-))

[rileykarson]

Make sure to update the release note!

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccSqlUser_postgresIAM You can view the result here: https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=211618

[modular-magician]

Tests failed during RECORDING mode: TestAccSqlUser_postgresIAM Please fix these to complete your PR