[llvm] Revert "LLVMContext: Cleanup registration of known bundle IDs" (PR #120396)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> > Can just remove the constexpr (or revert back to the original version which returned empty string)
> 
> I don't have an opinion. Whatever is better.

Remove the constexpr, it's not doing much 

https://github.com/llvm/llvm-project/pull/120396