Rollup merge of #41364 - alexcrichton:less-backtrace-prune, r=petrochenkov

std: Back out backtrace pruning logic

It was discovered #40264 that this backtrace pruning logic is a little too
aggressive, so while we figure how out to handle #40264 this commit backs out
the changes to prune frames. Note that other cosmetic changes, such as better
path printing and such remain.