When provider drivers registered a load balancer object delete,
the driver agent was not decrementing the project quota.
This patch corrects that by decrementing the proper quota
when a DELETED status is received from the provider driver.
Conflicts:
octavia/tests/unit/api/drivers/driver_agent/test_driver_updater.py
Change-Id: I7d705c9f4f0217c6fbe332f45b15892bf1d4a90b
Story: 2008268
Task: 41133
(cherry picked from commit fc8ee42dfc)
(cherry picked from commit 0a8254e04e)