Postgres-related alerts not to include version in hostname

• Please check this box if this contribution uses AI-generated content as outlined in the GitLab DCO & CLA

Issue: gitlab-com/gl-infra/production-engineering#25280

This fixes Postgres-related alerts, removing any version-related parts in the fqdn values – previously, it was 2004 (also suggesting that some alerts are not working since the PG12->PG14 upgrade). New version part is v14, but I think it's better to avoid that part completely, simplifying things for the future upgrades and hostname changes.

This needs to be well tested since without version, the coverage is wider – more hosts are to be involved (e.g., the nodes of the "embedding" cluster, which don't have version info, e.g., patroni-embedding-102-db-gprd.c.gitlab-production.internal).

cc @stejacks-gitlab @rmar1 @fomin.list @rhenchen.gitlab @alexander-sosna @bshah11