Auto-created GCSBucket inherits destination bucket storage class

[Vlad1mir-D]

Description:
Whenever GCSBucket (scratch bucket) created automatically, it inherits the storage class of the destination bucket.
Removal of temporary data from a scratch bucket which inherited nearline/coldline/archive storage class incurs additional costs for early data removal.

Reproducing:

1. Create GCS bucket with nearline storage class
2. Run GCP image export:

gcloud --project testproject compute images export --zone europe-north1 --export-format vmdk --image image_to_export --destination-uri gs://nearline_bucket/image_to_export.vmdk

Result:
A scratch bucket will be created with the same storage class as the destination bucket.

Expected result:
A scratch bucket should be created with a standard storage class.

Reproducibility:
100%