Add host validation after live migration

test_server_connectivity_live_migration was passing even in case
live migration was aborted e.g. like in case documented in [1].
This patch adds validation that server actually migrated.

[1] https://bugs.launchpad.net/tripleo/+bug/1852064

Change-Id: If6493ec4c849618fdd52a7e725f44537ab33d16a
1 file changed