Remove update_allowed_keys definition and usage

The update_allowed_keys attribute didn't really define any useful
policy, and prevented automatic update which should be handled by the
base Resource class like DeletionPolicy. This patch removes the usage
and the various definitions around the code base.

Change-Id: I78494aba07b6badeca8e95f1875ca8e4b9b0290c
Co-Authored-By: ala.rezmerita@cloudwatt.com
Partial-Bug: #1316171
Merge "Remove update_allowed_keys definition and usage"