Cells: Use tempest configs to turn off groups of tests that can't pass

[Andrew Laski]

Tempest has config options which allow for skipping tests that check certain functionalities. Examples at http://git.openstack.org/cgit/openstack/tempest/tree/tempest/config.py?id=841a15e82941bebe0fac8c248215b3b63ca30ad0#n319 . We should convert as much of the current cells blacklist regex into feature flags disabling the proper tests.

Currently the flags for the cells job will need to be added to devstack code in a "if n-cells enabled set these flags" sort of way. Longer term it would be nice to inject that config from Nova to keep the flexibility we currently have with the blacklist regex living in the Nova tree.

[Andrew Laski (alaski)]

With more thinking it may not be important to control the feature flags from the Nova repo. It's really nice to have a quick way to toggle tests from the Nova repo, but as long as the blacklist is there it will suffice.