The mixin dashboard uses metrics that don't exist

What did you do?
Run 0.13.2 in Kubernetes as a sidecar container via the postgres-operator.
Load this dashboard: https://github.com/prometheus-community/postgres_exporter/blob/master/postgres_mixin/dashboards/postgres-overview.json

What did you expect to see?
Something I could further tweak.

What did you see instead? Under which circumstances?
It appears all or nearly all the metrics this dashboard is looking for don't exist or are not being exported. - There are potentially similar ones being exported, but I might as well be starting from scratch because I can't know for sure if for example pg_stat_database_conflicts_confl_deadlock should replace pg_stat_database_deadlocks or what.

Environment

• System information:

  Linux 5.10.104-linuxkit x86_64

• postgres_exporter version:

  quay.io/prometheuscommunity/postgres-exporter:v0.13.2

• postgres_exporter flags:

--log.level=warn
--log.format=json

• PostgreSQL version:

  12,13,14

• Logs:
  no error logs

Start with postgres_mixin/dashboards/postgres-overview.json and compare every referenced metric with the metrics exported by postgres_exporter for PostgreSQL 12, 13, and 14. Determine the correct metric names and update the dashboard so its panels use metrics that are actually exported and display data.