Add postgres-pgvector images

What does this MR do and why?

These images are based on the code from https://github.com/pgvector/pgvector/blob/master/Dockerfile.

We need those for the AI experimentation effort (Context: gitlab!118156 (merged) and gitlab#404396 (closed)).

The plan is to replace our current postres image with postgres-pgvector images in CI to avoid setting up 2 different databases.

Checklist

• [-] (If applicable) Add patches if required for upgrading Ruby version in https://gitlab.com/gitlab-org/gitlab-build-images/-/tree/master/patches/ruby.