[llvm] [NFC] Add GIntrinsic::setIntrinsicID (PR #106236)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

See:
https://github.com/llvm/llvm-project/blob/81cd7358a2ce411c99512d055e98d0b9dc119c14/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp#L1635

If you want  to change properties of an existing instruction, you have to notify observers in GiSel.

https://github.com/llvm/llvm-project/pull/106236