Revert `QueryStackFrame` split
PR rust-lang/rust#138672 fixed a query cycle OOM reported in rust-lang/rust#124901. The fix involved delaying computation of some query stack frame elements and was very complex. It involved the addition of two new types, the addition of a generic `I` parameter to eleven(!) other types, a `PhantomData` field, and even required an unsafe transmute of a closure. [This comment](https://github.com/rust-lang/rust/issues/124901#issuecomment-2104852065) had suggested a much simpler fix, but it was ignored. The PR also failed to add a test case.
This PR adds a test case, reverts the complex fix, applies the simpler fix, and does a few other minor cleanups.
r? @oli-obk
Matthias Krüger
57e950bc98