Add issue priority as filter in Metric alerts

[rodolfoBee]

Problem Statement

Users want to create a metric alert that triggers when the number of error events reach a certain threshold. However, this limit can be rached by events from issues with low priority causing noise in the alert.

Solution Brainstorm

Add a filter option in the metric alerts configuration to take only events from issues with a determined priority. I see plans to add priority alerts, but this use case does not seem to be listed:
#63026
#74468

Product Area

Alerts

[getsantry]

Auto-routing to @getsentry/product-owners-alerts for triage ⏲️

[snigdhas]

We do already have priority alerts as a filter for issue alerts. AFAIK there are no plans to add priority as a consideration for metric alerts however.

[minori-fh]

Request for feature improvement: https://sentry.zendesk.com/agent/tickets/155267