Change conductor to cast to build_and_run_instance

With build_and_run_instance taking over for run_instance in the compute
manager, this switches over to calling it.  With this change the build
process will not cast back to the scheduler on a build retry.

This is the final part of a series of patches to build up the
build_and_run_instance method.

bp remove-cast-to-schedule-run-instance
Change-Id: Iefab71047996b7cc08107794d5bc628c11680a70
Merge "Change conductor to cast to build_and_run_instance"