Postgresql PeerAuthentication selector seems invalid

Summary

Kiali shows a warning that the PeerAuthentication selector doesn't match anything in the namespace. Either this is a historical remnant that is no longer needed, or should be conditionally created only when a postgres deployment exists.

Also noticed the peer-auth templates are not underneath the chart/templates/bigbang directory, which is where all bigbang custom templates should reside.

https://repo1.dso.mil/big-bang/product/packages/mattermost/-/blob/main/chart/templates/peer-authentication/postgres-exception.yaml?ref_type=heads

Steps to reproduce

Observed on dogfood cluster

What is the current behavior?

(What actually happens)

What is the expected behavior?

(What you should see instead)

Relevant logs and/or screenshots

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)

/cc {put CODEOWNERs @githandles here}