[clang] Re-apply "Emit missing cleanups for stmt-expr" and other commits (PR #89154)

[Utkarsh Saxena via cfe-commits]

usx95 wrote:

(addressed one more problem with conditional lifetime extension.)

> What, if anything, about the scenario you're describing is specific to "normal" cleanups?

We do not see this with `EHCleanup`s because `EmitBranchThroughCleanup` does not consider `EHCleanup`. It branches through all the "Normal" cleanups in the `EHStack`.

https://github.com/llvm/llvm-project/pull/89154