Rollup merge of #151390 - nnethercote:revert, r=petrochenkov

Reintroduce `QueryStackFrame` split.

I tried removing it in rust-lang/rust#151203, to replace it with something simpler. But a couple of fuzzing failures have come up and I don't have a clear picture on how to fix them. So I'm reverting the main part of rust-lang/rust#151203.

This commit also adds the two fuzzing tests.

Fixes rust-lang/rust#151226, rust-lang/rust#151358.

r? @oli-obk

Author: Zalathar