Stop the elastic-recheck bot more gracefully

* modules/elastic_recheck/files/elastic-recheck.init: It has in the
past been observed that the elastic-recheck IRC/Gerrit-commenting
bot does not always terminate cleanly. Use a retry with escalation
of kill signals in the initscript to help prevent additional old
processes from hanging around when restarts take place.

Change-Id: I9498eeeb935cb609c2c4c099c3552bed337fbe99
Merge "Stop the elastic-recheck bot more gracefully"