[XRay] Improve test matching granularity (NFC)

Simplify matchers for unittest to better isolate which differences there
are that we're finding in failures.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341237 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed