[CSSPGO] Tweakes to lower pseudo probe runtime overhead

A couple tweaks to

1. allow more thinlto importing by excluding probe intrinsics from IR size in module summary

2. Allow general default attributes (nofree nosync nounwind) for pseudo probe intrinsic. Without those attributes, pseudo probes will be basically treated as unknown calls which will in turn block their containing functions from annotated with those attributes.

Reviewed By: wenlei

Differential Revision: https://reviews.llvm.org/D109976