[PM] Fix new PM to perform SpeculativeExecution as in old PM

Summary:
Old PM runs SpeculativeExecutionPass for targets that have divergent branches.
It uses `createSpeculativeExecutionIfHasBranchDivergencePass` that creates
the pass with `OnlyIfDivergentTarget=true`, whereas new PM just created the
pass with default `OnlyIfDivergentTarget=fase` so it unexpectedly runs and
causes buildbot test fails.

Reviewers: chandlerc, arsenm

Reviewed By: arsenm

Subscribers: wdng, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D82735