[PowerPC][NFC] add an option to keep the test point

Passes before hardware loop insertion change the loop to a form which
is not a hardware loop candidate (return early before checking the ctr clobbers).
And the PHI in the loop exit block is also optimized away. This breaks the
previous test point when the case was committed. Fixing this by running this
case just before hardware loop insertion pass.

Reviewed By: nemanjai

Differential revision: https://reviews.llvm.org/D140366