20240207 honest leaf size

[IanDelbridge]

Relating to uplift trees/forests only:
Issue here. Currently, only results are modified when applying updated estimates via honestMethod. Since results does not include the number of samples, one cannot recover the full summary statistics for leaf nodes when using honestMethod. This information can be useful when investigating model behavior or post-hoc statistical analysis.

This PR would

1. change use fillTree in honestApproach, since that method already does all of the proper updating.
2. Since (1) would remove all code usages of modifyEstimation, that method is removed.

technically this is a breaking change since modifyEstimation was a public method.

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[CLAassistant]

All committers have signed the CLA.

[jeongyoonlee]

Thanks for your contribution, @IanDelbridge! Please sign the Contributor License Agreement (CLA) when you can.

[IanDelbridge]

Of course, @jeongyoonlee! I just needed to confirm with my company's legal team before signing. The CLA is signed now.

[jeongyoonlee]

LGTM.