Use histogram metrics for Scores in Bazarr Exporter

[rtrox]

Details

What steps did you take and what happened:

While working on some other things, I noticed this -- right now we're exporting counts of episodes/movies by score -- like other *arrs, score is a percentage indication of certainty, and at least in bazarr, it has 2 decimals of precision. This means cardinality for this label could theoretically hit 10k.

Graphing this metric is likely to be done via pie chart / bar distribution, which means a quantile a) bounds cardinality to bucket count, and b) is actually a bit better representation of this type of value anyway.

Additional Information

Prometheus Quantiles: https://prometheus.io/docs/practices/histograms/
MustNewConstHistogram: https://pkg.go.dev/github.com/prometheus/client_golang/prometheus#MustNewConstHistogram
Example Usage: https://github.com/prometheus/client_golang/blob/main/prometheus/examples_test.go#L440-L446 (note: bucket labels are an inclusive upper bound)

Reference

exportarr/internal/arr/collector/bazarr.go

Lines 335 to 348 in e42774b

	// just shove them into episode stats to avoid extra looping
	if len(movieStats.scores) > 0 {
	for score, count := range movieStats.scores {
	episodeStats.scores[score] += count
	}
	}
	if len(episodeStats.scores) > 0 {
	for score, count := range episodeStats.scores {
	ch <- prometheus.MustNewConstMetric(collector.subtitlesScoreMetric, prometheus.GaugeValue, float64(count),
	score,
	)
	}
	}

[rtrox]

Dropping this here for now. This will technically be a breaking change, but given how new the bazarr collector is, I doubt we have more than a few folks graphing it. I'd like to get this in somewhat quickly to keep it that way.

Marking help wanted as (again) I don't actually have a bazarr instance to test with, but I'm off this week, so if this isn't picked up quickly, I'll spin up a test instance later this week and make this change.

[codefaux]

I run Bazaar (every exporter you implement actually) and am willing to help however I can, but I'm unable to glean your ask from the messaging here. If you still desire a test platform, let me know how I can help.