Revert "Update test_debuginfo.pl script to point to new tree location."

This reverts the aforementioned patch and 2 subsequent follow-ups,
as some buildbots are still failing 2 tests because of it.
Investigation is ongoing into the cause of the failures.

llvm-svn: 318112
GitOrigin-RevId: faf04a09f69c07f66c81167f5875518102675911
22 files changed