Rewrited mox tests to mock (part 2)

This is second and last part of removing mox
module from manila's dependencies, that became deprecated.
Rewrote unittests for scheduler, fixed and enabled them.

Partially implements: blueprint replace-mox-with-mock
Change-Id: Ida60abaa287e42a42c59f900bb168992575e311e
Merge "Rewrited mox tests to mock (part 2)"