cloud/bmaas/bmdb/scruffy: initialize, implement BMDB metrics

This creates a new BMaaS component, Scruffy the Janitor.

Scruffy will run a bunch of housekeeping jobs that aren't tied to a
particular provider or even region. Currently Scruffy just collects BMDB
metrics by periodically polling the BMDB SQL database.

Change-Id: Icafa714811757eaaf31fed43184ded8512bde067
Reviewed-on: https://review.monogon.dev/c/monogon/+/1819
Tested-by: Jenkins CI
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
diff --git a/cloud/bmaas/bmdb/metrics/metrics.go b/cloud/bmaas/bmdb/metrics/metrics.go
index 2dbad29..509827b 100644
--- a/cloud/bmaas/bmdb/metrics/metrics.go
+++ b/cloud/bmaas/bmdb/metrics/metrics.go
@@ -26,6 +26,7 @@
 	ProcessorShepherdRecoverer   Processor = "shepherd-recoverer"
 	ProcessorShepherdUpdater     Processor = "shepherd-updater"
 	ProcessorBMSRV               Processor = "bmsrv"
+	ProcessorScruffyStats        Processor = "scruffy-stats"
 )
 
 // String returns the Prometheus label value for use with the 'processor' label