Update prometheus version to 15.0.4

What does this MR do?

Update the Prometheus Helm chart prometheus-community/prometheus from 11.16.9 to 15.0.4, which brings us from application 2.21.0 to 2.31.1

There is an "Upgrade to 15.0" step that should be taken into account, as this includes a direct kubectl delete deployments.apps call

Related issues

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened