Per T239453#5910993 we should look at removing these groups from the MW db lb configs:
- contributions
- logpager
- recentchanges
- recentchangeslinked
- watchlist
That would leave us with:
- api
- dump
- vslow
This would greatly simplify automating depooling/repooling db instances.
## Outcome
* [x] Confirmation and understanding that these configs are functionally safe to remove in productrion without requiring any code changes, even if they are still referenced. To be walk through by by @Krinkle together with one or two people from PET as part of knowledge transfer and familiarity with #wikimedia-rdbms.
* [x] Understanding and agreement on which of these (if any) we need to keep, and why. To be carried out by #platform_engineering based on the history of the db index and its usage in code.
* [x] {T267077}
* [ ] Remove obsolete db group parameters from MW core and WMF-deployed extensions.
Removal progress
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