Fix test_force_detach_volume_from_instance

This commit fixes test_force_detach_volume_from_instance errors
by making the following changes to the test:
  - adding a waiter following the force_detach
  - creating a test-level volume

This way, race conditions associated with the volume's status
are eliminated and the class-level volume isn't put into error
state causing other tests to fail.

Change-Id: Ia046b114761937dc5f7b837892c53a5a508c5114
1 file changed