[coro async] Don't use lifetime.start based alloca localization for ABI.Async/ABI.Retcon

Infinite loops can lead to an IR representation where the lifetime.end
intrinsice is missing. The code to do lifetime based optimization then
fails to see that an address escapes (is life) accross a supspend.

Eventually, we could detect such situations and disable it under more narrow
circumstances. For now, do the correct thing.

rdar://83635953

Differential Revision: https://reviews.llvm.org/D110949