[Test][Time profiler] Fix test for python3

Summary:
Fix test checking time profiler generates correct tracing json-file.
`filter` works differently for python2 and python3, so unifying this.

Reviewers: mgehre, nathanchance

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66873

llvm-svn: 370300