Fix for DC2022

Missed part of config for DC2022; corrected here.

Enabling DC monitoring

Again we're running our DC in the cloud. Consequently, this release re-enables the collection of the DC data.
(Note, the DC dashboard is still named DC2020 - keeping with tradition ;)

Removal of Luigi functionality

UKWA has moved away from Luigi scheduling and thus this release removes the Luigi alerts.

Improve WARC backlog alerting

Release covering #38

Removal of completed DC2021 jobs

As DC2021 has now completed, removed server from monitoring.

Airflow and Nominet updates

Commenting out of Nominet updates as currently not in use.
Alteration of production airflow service as now running off prod swarm.

From #37

Alert rules update

Update related to github issue #36.

Alert rules update

Updates for issues 33 and 35.

Hadoop 3 release - fix

Due to our github rate limit issue, I've removed the alertmanager version to make this service successfully start.

Addition of Hadoop 3 monitoring

Our new Hadoop 3 cluster should be monitored, to identify namenode and datanode issues. This release adds a baseline monitoring service for Hadoop 3.