[clang] [lld] [llvm] [LTO] enable `ObjCARCContractPass` only on optimized build (PR #101114)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

Is there some way we can avoid the additional domtree construction? Particularly in cases where the pass doesn't do anything.

https://github.com/llvm/llvm-project/pull/101114