Add oslo db retry decorator to non-CRUD actions
The previously added decorators to the create and update handlers
in the API layer only applied to actions that followed the standard
create/update path. However, for API operations like add_router_interface,
a different path is followed that wasn't covered by a retry decorator.
This patch adds the decorator to handle deadlocks in those operations as
well.
Closes-Bug: #
1475218
Change-Id: Ib354074e6a3f68cedb95fd774f905d94ca16a830
(cherry picked from commit
435ffa7c67cf8668063588e2af760c1ff595dfbb)