[llvm] [X86] Don't always separate conditions in `(br (and/or cond0, cond1))` into separate branches (PR #81689)

[Shengchen Kan via llvm-commits]

KanRobert wrote:

> This will also likely help for APX targets with the new CCMP and
CTEST instructions.

In fact, this causes some downstream CCMP tests to fail b/c branch is already eliminated. @goldsteinn Is there a flag to undo the change in test?

https://github.com/llvm/llvm-project/pull/81689