V2 Boot from volume overhaul

* Skipping tests with known issues in negative tests
* Checking for not supported glance snapshot change
* Moving all V2 tests to not directly call compute clients
* Removing double line
* Changing response codes check from 202 to 200 because of clients vs behaviours use

Change-Id: Idd6d36a629794c50fce315d2c82c6390fbffb12f
Merge "V2 Boot from volume overhaul"