tests: ask any chg instance to terminate before looking at sqlite dbs

There are spurious errors in CI where the database is still locked, so
force the daemon to quit to get deterministic behavior. Since the kill
command itself is racy, also sleep 2s to give the server time to wake up
and exit.
23 jobs for topic/default/fix-chg in 33 minutes and 13 seconds (queued for 4 seconds)