make provisioning_model o+c

[shuyama1]

This field was added in PR #5662
Some of the tests start to fail in our nightly tests due to permadiff https://ci-oss.hashicorp.engineering/buildConfiguration/GoogleCloudBeta_ProviderGoogleCloudBetaGoogleProject/255295?buildTab=tests&status=failed&name=TestAccComputeInstance&pager.currentPage=1&expandedTest=-3022451123674774073
Therefore, making the field optional + computed.

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)

compute: fixed permadiff in `google_compute_instance.scheduling.provisioning_model`

[modular-magician]

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

Diff report:

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

[modular-magician]

I have triggered VCR tests in RECORDING mode for the following tests that failed during VCR: TestAccDataSourceGoogleFolder_lookupOrganization|TestAccDataSourceGoogleFolders_basic|TestAccDatasourceGoogleServiceNetworkingPeeredDnsDomain_basic|TestAccApigeeEnvironmentIamBindingGenerated|TestAccApigeeEnvironmentIamMemberGenerated|TestAccApigeeEnvironmentIamPolicyGenerated|TestAccCloudbuildWorkerPool_basic|TestAccComputeInstance_guestAccelerator|TestAccComputeInstance_guestAcceleratorSkip|TestAccComputeRegionNetworkEndpointGroup_negWithServerlessDeployment|TestAccContainerCluster_withAuthenticatorGroupsConfig|TestAccFolderIamAuditConfig_addFirstExemptMember|TestAccFolderIamAuditConfig_removeLastExemptMember|TestAccFolderIamBinding_basic|TestAccFolderIamMember_basic|TestAccServiceNetworkingPeeredDNSDomain_basic|TestAccSqlDatabaseInstance_withPrivateNetwork_withAllocatedIpRangeReplica|TestAccSqlDatabaseInstance_withPrivateNetwork_withAllocatedIpRangeClone|TestAccSqlDatabaseInstance_withPrivateNetwork_withAllocatedIpRange|TestAccStorageTransferJob_posixSink You can view the result here: https://ci-oss.hashicorp.engineering/viewQueued.html?itemId=254920

[shuyama1]

@rileykarson This field will be release next Monday. Do we need to cherry pick this fix to include it in the next release, as this is a ForceNew field? (The tests passed in the VCR tests when we tested them last week, but start failing from Tuesday. Plus this is also partially optional computed, as these three are the only tests fail)

[rileykarson]

Yeah, we'll want to cherry-pick it or revert the original change from the release branch. You can work out the option to take w/ BOD! FYI @melinath

[shuyama1]

Yeah, we'll want to cherry-pick it or revert the original change from the release branch. You can work out the option to take w/ BOD! FYI @melinath

Thanks @rileykarson ! I'll discuss with @melinath on this!

[melinath]

Closing the loop - we decided to revert this from the 4.11.0 release.