Validate backup/restore with PG16

We are adding PG16 as an option post GitLab 17.x, and need to support backup/restore with PG16.

The current procedure should not need to be deviated from significantly.

We should verify the following installation types:

  1. Single node
  2. Multi-node

Last time we did this for PG14, Validate backup/restore with PG14 (#429887 - closed)

Edited by John Jarvis