[clang] [llvm] [polly] [DebugInfo] Remove dead debug intrinsic handling (NFC) (PR #231379)

[Alexis Engelke via cfe-commits]

https://github.com/aengelke approved this pull request.

LGTM. Is DXIL the only remaining user? (We also have Instruction::isDebugOrPseudoInst(), which should (probably separately) be replaced with `isa<PseudoProbeInst>()` or removed (with preference to removal).)

https://github.com/llvm/llvm-project/pull/231379