Tweak solr weights/boosts - switch from additive boosting to multiplactive boosting

[cdrini]

Closes #11777

Technical

• Previously, we used the bf parameter for our boosting, but this applied additive boosting, meaning the boosting could outweight the relevance quite drastically. Switching to boost gives us multiplicative boosting, which is recommended. See Additive Boosts vs Multiplicative Boosts
• Note there is some performance concern since we are (1) using a lot of fields in our qf, where previously we only had a few, and (2) using more pf fields. If there is too much of a performance cost, we can switch back to using text ; there is still a big improvement from the boosting changes alone.

Testing

Improves upon all classes in our evaluation spreadsheet. C in the following tables (Note A is the same as C, but using text instead of the explicit listing of fields.)

You can also compare results before/after here: https://codepen.io/cdrini/full/wvJqzaK

Screenshot

Stakeholders

[Copilot]

Pull request overview

Adjusts Work Search’s Solr eDismax tuning to use multiplicative boosting (via boost) instead of additive boosting (via bf) to reduce over-weighting of popularity signals relative to textual relevance.

Changes:

• Replaces bf-based additive boosts with an eDismax boost function expression.
• Expands/adjusts qf and phrase-boost parameters (pf, pf2) to change match weighting and proximity scoring.

[cdrini]

Patching this out now for a bit to monitor performance.

[mekarpeles]

Here's an example @cdrini showed where the search was "The secret of secrets" which didn't appear within the first 15 results on (before) and is 3rd on (after)