Run identity client relations when db is complete

When keystone is deployed with multiple units but without hacluster one
off scenarios occur where one non-leader unit will fail to update its
client relations.

This change runs all identity client relations when the database
relation is complete thus guaranteeing all keystone units update there
identity relation data with clients.

Small timing fix to amulet tests.

Closes-Bug: #1761562
Change-Id: I338e500dbc155b75c75b9261a9b5b471bd73088a