adopt: stop iscsi services in the first place

adopt: stop iscsi services in the first place

If old containers are still running, it can make tcmu-runner process
unable to open devices and there's nothing else to do than restarting
the container.

Also, as per discussion with iscsi experts, iscsi should be migrated before
OSDs. (the client should be closed before the server)

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2000412
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit d12efa1ab4fb6c4641d05ba07cb32db9fd1aa409)