Make scheduler modules pass conductor to add_instance_fault

The add_instance_fault_from_exc() method was recently changed to
take a conductor to avoid direct database access. The scheduler was
not updated for this, and thus was not passing it in a couple of
cases.

This makes those calls pass a conductor LocalAPI, resulting in direct
database access (which is desired from the scheduler). The tests that
one might have thought would catch this didn't because they mock out
the method itself. This fixes those and adds two tests that exercise
the add_instance_fault path all the way down to the DB API, which
would have caught it in the first place.

Fixes bug 1110808

Change-Id: If1c2988487d408a39fdf4080541f58f6bdac216c
Merge "Make scheduler modules pass conductor to add_instance_fault"