removed tiering creation with default bucket class for namespace bucket

[dannyzaken]

• when creating a namespace bucket with OBC the provisioned created a dummy tiering policy with the default bucket class. this was to work around a bug in noobaa core where the internal resource was assigned to the bucket, but it doesn't exist in OCD DS.
• removed the tiering creation for namespace resource and fixed the issue in noobaa-core - skip tiering creation for namespace buckets noobaa-core#6663

fix for https://bugzilla.redhat.com/show_bug.cgi?id=1981331