Fix failing container cluster tests

[c2thorn]

fixes hashicorp/terraform-provider-google#11897
fixes hashicorp/terraform-provider-google#11898

The following tests started failing after API updates:
TestAccContainerCluster_withAddons
Fails with an internal error due to hashicorp/terraform-provider-google#11943

TestAccContainerCluster_withConfidentialNodes
node_config's min_cpu_platform can return a value from the API now.

container: fixed an issue where `node_config.min_cpu_platform` could cause a perma-diff in `google_container_cluster`

[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, 50 insertions(+), 45 deletions(-))
Terraform Beta: Diff ( 2 files changed, 50 insertions(+), 45 deletions(-))
TF Validator: Diff ( 2 files changed, 3 insertions(+), 3 deletions(-))

[modular-magician]

Tests analytics

Total tests: 2062
Passed tests 1831
Skipped tests: 226
Failed tests: 5

Action taken

Triggering VCR tests in RECORDING mode for the tests that failed during VCR. Click here to see the failed tests

TestAccFirebaserulesRelease_BasicRelease|TestAccContainerCluster_withAddons|TestAccContainerCluster_withConfidentialNodes|TestAccPrivatecaCertificateAuthority_subordinateCaActivatedByFirstPartyIssuerOnCreation|TestAccPrivatecaCertificateAuthority_privatecaCertificateAuthoritySubordinateExample

[modular-magician]

Tests passed during RECORDING mode:
TestAccContainerCluster_withAddons[view]
TestAccPrivatecaCertificateAuthority_privatecaCertificateAuthoritySubordinateExample[view]
TestAccPrivatecaCertificateAuthority_subordinateCaActivatedByFirstPartyIssuerOnCreation[view]
TestAccFirebaserulesRelease_BasicRelease[view]
TestAccContainerCluster_withConfidentialNodes[view]

All tests passed
View the build log or the debug log for each test