Merge test_snapshot_create_with_volume_in_use

test_snapshot_create_with_volume_in_use can be mostly
covered in test_snapshot_delete_with_volume_in_use, except
"Snapshot a volume which attached to an instance with
 force=False", so this is to move that test step to
test_snapshot_delete_with_volume_in_use and remove
test_snapshot_create_with_volume_in_use, so the total
run time can be reduced.

These two testcases are not used in the newest defcore
json files.

Change-Id: Ib04fe2d2127681cd89bfea3cc2d09f4aafbc6f34
1 file changed