feat: add autovac worker metrics to sql_exporter and grafana (#409)

* feat: add autovac worker metrics to sql_exporter * feat: add autovac worker panel to grafana dashboard * fix: revert change to datasource variable * fix: revert change to datasource variable --------- Co-authored-by: Douglas J Hunley <doug.hunley@gmail.com>

Author: keithf4

changelogs/fragments/106.yml

@@ -0,0 +1,3 @@
+minor_changes:
+ - sql_exporter - Add metrics to track current autovacuum workers running and max autovacuum workers
+ - grafana - Add panel to PG Details dashboard to track autovac workers running vs max