Recommit "[X86] Don't always separate conditions in `(br (and/or cond0,...

Recommit "[X86] Don't always separate conditions in `(br (and/or cond0, cond1))` into separate branches" (2nd Try)

Changes in Recommit:
    1) Fix non-determanism by using `SmallMapVector` instead of
       `SmallPtrSet`.
    2) Fix bug in dependency pruning where we discounted the actual
       `and/or` combining the two conditions. This lead to over pruning.

Closes #81689