[CSSPGO] Flip SkipPseudoOp to true for MIR APIs.

Flipping the default value of SkipPseudoOp to true for those MIR APIs to favor maximum performance. Note that certain spots like branch folding and MIR if-conversion is are disabled for better counts quality. For these two optimizations, this is a no-diff change.

The counts quality with SPEC2017 before/after this change is unchanged.

Reviewed By: wmi

Differential Revision: https://reviews.llvm.org/D100332