[unittests] Add InitializePasses.h includes

Summary:
After D70211, Pass.h does not include InitializePasses.h anymore, so
these files need to include InitializePasses.h directly.

Reviewers: rnk

Subscribers: MatzeB, mehdi_amini, zzheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70217