🌱 Add priority label to PQ depth metric

[sbueringer]

Part of #2374

[sbueringer]

/assign @alvaroaleman
for an initial review

/hold

[alvaroaleman]

Looks good but one comment re double registration

[alvaroaleman]

Are you sure that prometheus allows to register the same metric twice in general and in particular with different labels?

[sbueringer]

Very good point. This only "worked" because I forgot to register the new metric

[sbueringer]

Now I'm only using one metric. The result is the following

Metrics endpoint

# controller with enabled PQ:
workqueue_depth{controller="cluster",name="cluster",priority="0"} 0
# controller with disabled PQ:
workqueue_depth{controller="machine",name="machine",priority=""} 0

Prometheus

Labels with an empty label value are considered equivalent to labels that do not exist.
https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels

OpenMetrics

Empty label values SHOULD be treated as if the label was not present.
https://github.com/prometheus/OpenMetrics/blob/main/specification/OpenMetrics.md#label

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 11dae92c12c13005b9969a10867bd6ac5d763a5a

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alvaroaleman, sbueringer

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[sbueringer]

/hold cancel