[#69625846] Adding server checks to postgres and backups
[#69625846] Adding server checks to postgres and backups

- Fortunately these checks should largely be token additions, as we already have criticals around `stagecraft_access_data_sets_health_check` on the backend app boxes, and a `keepalive` check hanging around.
- These should inform us something is wrong, but it's good to know that the box being down is the root cause.
- Now if only I could figure out how to remotely restart the box :-/

alphagov/pp-puppet,alphagov/pp-puppet,alphagov/pp-puppet,alphagov/pp-puppet