[llvm] [TableGen] Rework `EmitIntrinsicToBuiltinMap` (PR #104681)

[Rahul Joshi via llvm-commits]

jurahul wrote:

> > Does it make any measurable performance difference in practice? If not, readability wins.
> 
> I mean this is generated code, the readability doesn't really matter at all

Yeah, I did not say that explicitly. Readibility may not matter here as much. In which case space savings win. But I'll let the matter settle between @arsenm and @Artem-B and I am happy to do what the reviewers decide.

https://github.com/llvm/llvm-project/pull/104681