[lld] [lld][COFF] Don't truncate .llvm. and llvm_ section names (PR #229112)

[Saleem Abdulrasool via llvm-commits]

compnerd wrote:

Is it not possible to consider a compliant name on PE/COFF? `.lloffld` or `.offload` would fit the constraints and while it shuffles the work to the consumer, it remains more portable.

https://github.com/llvm/llvm-project/pull/229112