add forum notifier to prod and stage workers

removing git accounts for notifier repo, open now

add datadog api key Since this file will be the model for others
to use for their vars files, put in a placeholder DD api key, since
it's required to be *something* currently.

celerybeat wants to write its pidfile to ~notifier/src.  Not sure why
the PID or CELERYD_PID_FILE environment variables don't correctly point
it to /var/run/... but in the meantime, this should get us by.

notifier: remove git_ssh wrapper not needed now that repo is public

run notifier on first util machine only

remove references to forums_digest.sh. File was a vestige of prior
code when this was run from cron instead of celery beat.
Fix var name for jdk link.
fix worker name for notifier, util1 --> util10