[llvm] [Coroutines] Make CoroElide actually work for (trivial) C++ coroutines (PR #92969)

[via llvm-commits]

WenleiHe wrote:

Has the work list search limit (`Limit = 32 * (1 + It->second.size())`) for escape ever turn out to be a problem? 

https://github.com/llvm/llvm-project/pull/92969