[llvm] [Coro] Amortize debug info processing cost in CoroSplit (PR #109032)

[Felipe de Azevedo Piovezan via llvm-commits]

felipepiovezan wrote:

Hi @artempyanykh, while I follow Adrian's suggestions, you could extract the first commit into a separate PR and we'll start reviwing/merging the NFC stuff one by one

https://github.com/llvm/llvm-project/pull/109032