[llvm] [RFC][GlobalISel] Use Builders in MatchTable (PR #65955)

[via llvm-commits]

https://github.com/qcolombet requested changes to this pull request.

I think it makes sense to use `MachineInstrBuilder` in general.
Regarding Observes, I think it makes sense (maybe?) to use them to manage the worklist of things that needs to be combined/selected, but it is a no-no IMHO for flag propagation.

https://github.com/llvm/llvm-project/pull/65955