previously, delayed_job restart/stop would fail if the pid file was
there, but the process didn't exist
test plan: start delayed jobs, then kill -9 the pool. then try
restarting delayed jobs, it'll still be successful.
Change-Id: Iaedbdc6c0381a6f79ab488eefd19344645e3e2df
Reviewed-on: https://gerrit.instructure.com/8266
Reviewed-by: Brian Palmer <brianp@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Tested-by: Hudson <hudson@instructure.com>