tests: Fix failing test_exit_status

This test assumed that after removing the metadata.mfs file and starting
the master server it would fail and leave the working directory in
a "dirty" state which can only be fixed by metarestore. This is no
longer true, so the test needs to be updated.

Change-Id: I1c9e109c015f6c020498cce507f5bc655ed8c3a4