fix: claims logic when total_fees are greater than total_tips (#169)

**Problem**
The amount to pay out to vote account claimants is not calculated
correctly when total_fees exceed total_tips. This scenario manifests
when validator commission bps on tip distributions is set to 10_000.

**Solution**
- Subtract protocol fees from vote account claimant payouts when total
fees exceed total tips
- Test case for 10_000 bps commission on tip distribution
- Test case for legacy calculation (feature gated at epoch 815)

Author: gzalz