Make live_migrate_server() use common method
Make live_migrate_server() use common method

There is a common method action() for calling action API.
This patch makes live_migrate_server() use it for cleanup.

Change-Id: I5d1d23d3a6e4f7efa6e3119db3a2f393c3e4fe69

Juniper/tempest,bigswitch/tempest,masayukig/tempest,cisco-openstack/tempest,openstack/tempest,vedujoshi/tempest,masayukig/tempest,Juniper/tempest,zsoltdudas/lis-tempest,LIS/lis-tempest,zsoltdudas/lis-tempest,vedujoshi/tempest,openstack/tempest,sebrandon1/tempest,bigswitch/tempest,Tesora/tesora-tempest,Tesora/tesora-tempest,sebrandon1/tempest,LIS/lis-tempest,cisco-openstack/tempest