[clang] [clang][HeuristicResolver] Track the expression whose type is being simplified after each step in simplifyType() (PR #126689)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

The explanation in [this comment](https://github.com/llvm/llvm-project/issues/126536#issuecomment-2649966528) may provide useful context for reviewing this fix.

https://github.com/llvm/llvm-project/pull/126689