[llvm] InstrProfiling: Split creating Bias offset to getOrCreateBiasVar(Name). NFC. (PR #95692)

[NAKAMURA Takumi via llvm-commits]

chapuni wrote:

@ornata 
I didn't think I have to write RFC.

Do you want me to post the RFC before reviewing this NFC change?

https://github.com/llvm/llvm-project/pull/95692