Move restart_service to the end of the promote
This moves the restart_service stage back to the end of promote. This:
- Avoids making an additional ssh connection to restart a service (even if no service is provided)
- There are services that may require a restart to being reading new code, which may make a separate restart stage difficult to handle.
This should retain the ability to run post-promote and post-service
restart check commands.
Also, adds the deploy --service-restart flag, to restart the service
Reviewers: mmodell, demon, Release-Engineering-Team, dduvall
Reviewed By: Release-Engineering-Team, dduvall
Differential Revision: https://phabricator.wikimedia.org/D148