[PGO][PGSO] Distinguish queries from unit tests and explicitly enable for the...

[PGO][PGSO] Distinguish queries from unit tests and explicitly enable for the existing IR passes only. NFC.

Summary:
This is one more prep step necessary before the code gen pass instrumentation
code could go in.

Reviewers: davidxl

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70988