Wait server to be terminated in VolumesV2NegativeTest.

In some cases, it takes some time to delete server. This might
cause the tear down class fail to delete other resource. Wait
the server to be terminated in test case can avoid this failure.

Change-Id: I10e87cf792f90edc2b5db208205c7425f1a6cec5
Closes-Bug: #1471712
1 file changed