Currently, coderd/metricscache/metricscache_test.go runs tests against the dbmem implementation only. This is an issue as the implementation of GetTemplateAverageBuildTime has diverged between dbmem and Postgres.

The divergence occurred here #14576, when dbmem moved to a continuous percentile instead of a discrete percentile. It is worth noting that the original dbmem implementation also exhibited slightly different behavior than Postgres as it calculated the discrete percentile slightly differently, although this likely wasn't spotted as the test wasn't ran on Postgres.