Add task-failed-because-no-data metric

[nritsche]

This is so that tasks failing with a DiasDataError can produce a different alert (see #93).

[nritsche]

I created separate alerts here: https://github.com/CHIMEFRB/frb_ansible/pull/26

It expects the dias_task_failed_total metric but also a new one called dias_task_no_data_total.