Use correct project/user id in conductor.manager

The project/user id of the user is not passed to the quotas.rollback
methods in conductor/manager.py if the instance is migrated by admin.
This fixes the issue by using the new quotas object to ensure the
right project/user id.

Change-Id: Ifdcfb62ed7eb0710bfdd921b0213be240a00345c
Closes-bug: 1296502
Merge "Use correct project/user id in conductor.manager"