[llvm] Reapply [TLI] Fix replace-with-veclib crash with invalid arguments (PR #77945)

[Paschalis Mpeis via llvm-commits]

paschalis-mpeis wrote:

@pranavk  glad that we exposed a bug inadvertently.

We programmatically check the  debug output of a pass that we test, hence, we enabled it in code.
But it's true that it's not widely used. I opened a pull request that should not 'leak' the state of the debug flag on subsequent passes:
- #78989

https://github.com/llvm/llvm-project/pull/77945