Reviewing the features used by the UMA Sampling Profiler Predator support I found a few issues:

1. The TopFrameIndex feature doesn't operate as expected since the feature expects the frame indices to increment from 0 from leaf up. The UMA Sampling Profiler currently sets the indices to the frame depth from root down, and excludes indices above the  regression subtree root. I believe the practical effect is that this feature will evaluate to 0 on nearly all stacks because most regression subtrees do not have indices with the range of [0, 7] which are the min and max indices used by the rule.

Independent of this, we probably don't want to use this feature anyway because it does the opposite of what we'd want, which would be to provide a slight bias towards matches closer to the subtree root. We can remove it for now and later consider reintroducing a different rule creating a preference for nodes closer to the subtree root if this seems like it would be useful.

2. The NumberOfTouchedFiles feature also is probably not useful for the UMA Sampling Profiler. CLs that touch many files are as likely as smaller CLs to introduce changes that we want to detect, particularly refactoring changes that change function signatures. In that case it's important to detect that the removal of the old signature and the addition of the new signature were introduced by the same CL. So we should remove this feature also.

3. The TouchCrashedComponentFeature is specified but no weight is provided. I don't expect this feature to be very useful so think we can remove it as well.