Move ovs-cleanup step to cleanup-containers,
otherwise bridges will not be removed because neutron_openvswitch_agent
container does not exists after running cleanup-containers.

Add logic to cleanup ovs bridges only when openvswitch_db
is removed and openvswitch-agent is running,
so when removing other container from a parameter at script
invocation ovs-cleanup will not be executed.

Change-Id: Ie5fea40426df0e9e465fc173aba185f61098f676
Closes-Bug: #1640178