Test Postgres 12 and Patroni to evaluate adding to Reference Architectures
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In an attempt to be a bit more proactive it was discussed in passing that Postgres 12 and Patroni should be available as an option in 13.3. We want to performance test these as soon as possible (when available in the omnibus nightly packages) like [we did for PG11](https://gitlab.com/gitlab-org/quality/team-tasks/-/issues/389).
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