relation-list only takes one argument, so iterate through, doing a db-proxy-relation-changed if we have a match
some fixes for the backend-db-admin-relation-changed hook, and we also need to fix db-proxy-relation-changed
Whitespace and indenting cleanup
Merging MP:155205. If we have more than one db-proxy relation, the charm fails because we get the output of "relation-ids db-proxy" and pass that to "relation-list -r", which only accepts one relation id at a time. So, this fixes that problem.