[llvm] [RegisterCoalescer] Deferring deletion of instructions in `ErasedInstrs` until the end of an iteration (PR #79820)

[Quentin Dian via llvm-commits]

DianQK wrote:

> #73519 is potentially another attempt at solving the same issue

It does seem to be the same issue. I'm not sure which is the better way to handle this. Do you have any more suggestions?

(This PR seems to be missing multiple duplicates?)

https://github.com/llvm/llvm-project/pull/79820