feat: add pgbouncer.statsUsers value to set stats_user in pgbouncer

[jbvaningen]

What issues does your PR fix?

• fixes Enable querying of PgBouncer metrics by supporting additional PgBouncer configuration #819

What does your PR do?

This PR adds the following values:

• pgbouncer.statsUsers (default: "")
  • Sets the stats_users PgBouncer config in the pgbouncer.ini file.

Checklist

For all Pull Requests

• Commits are signed off
• Commits have semantic messages
• Documentation updated
• Passes ct linting

For releasing ONLY

• Chart.yaml version bumped
• CHANGELOG.md updated

[jbvaningen]

@thesuperzapper are you or somebody else available to review this PR please?

[stale]

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It will be closed in 7 days if no further activity occurs.

Thank you for your contributions.

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[jbvaningen]

@thesuperzapper we are still interested in getting this merged. Is anyone available to review this?

[thesuperzapper]

@jbvaningen sorry for missing this!

We are currently trying to get airflow 2.9 working in a new release, so I guess this could be part of that.

Is this single config really all you need?

Is there anything else we should add or another way of doing this?

[jbvaningen]

@thesuperzapper nice!

yes this single config is all that is needed to support pgbouncer metrics exporting.

[thesuperzapper]

@jbvaningen thanks, I pushed a small cosmetic update in d43bbf3, but this is good to merge.