BucketPolicyOnly: fix broken requests to update BPO enabled field.

[frankyn]

Hi @quartzmo,

Last week, a system test was skipped due to a backend bug (#3772) . The backend bug will take another 3 weeks based on my last conversation with the GCS team.

In the mean time a workaround should be put in place to reduce impact on users.
When performing an update on the BPO field (enable or disable), the UniformBucketLevelAccess field must be set to the same value as the BPO field during an Update or Patch request.

Here's an example patch:
PATCH uri
Body:

{
"iamConfiguration":
  {
     "bucketPolicyOnly": {"enabled": true},
     "uniformBucketLevelAccess": {"enabled": true}
  }
}

Related issue in Python: googleapis/google-cloud-python#8552

[quartzmo]

Thanks @frankyn, will do!

[quartzmo]

@frankyn When BucketPolicyOnly#locked_time is set, should it be set to the same value in UniformBucketLevelAccess?

[frankyn]

locked_time is defined by the service and is not a user mutable field.

[quartzmo]

Ah sorry to bother you, I just realized that too.

[frankyn]

Not a problem, thanks for asking. Thanks for taking a look at this @quartzmo.