[SampleFDO] Skip PreLink ICP for better profile quality of MonoLTO PostLink

For ThinLTO, PreLink ICP is skipped to favor better profile annotation during LTO PostLink. This change applies the same tweak for MonoLTO. Note that PreLink ICP not only makes PostLink profile annotation harder, it is also uncoordinated with PostLink ICP so duplicated ICP could happen.

Differential Revision: https://reviews.llvm.org/D97028