[llvm] Scalarizer: Replace cl::opts with pass parameters (PR #110645)

[Farzon Lotfi via llvm-commits]

farzonl wrote:

We intentionally brought back the old pass manager semantics. The directX backend is still experimental so if someone removes the legacy pass manager our builds will break silently.  Our thinking was keeping around the legacy flag makes it so someone has to grep the codebase before removing.

https://github.com/llvm/llvm-project/pull/110645