Previously the merger docker-compose restart value was set to always.
This caused the merger to immediately restart after asking it to
gracefully stop and our check for the merger stopping:
docker-compose ps -q | xargs docker wait
never saw it as being stopped.
Make the mergers match executors and restart only on failure. This
should allow us to gracefully stop the mergers with intention and detect
they are stopped for maintenance purposes.
Change-Id: Ia8d12fbf6a45e4ca85174ccafd18b5d2351c26c1
761dbb4352