Revert "Stabilize output of new regression test case".

Revert "Stabilize output of new regression test case".

This effectively reverts commit 9edc97b71 (although the test is now
in a different place and has different contents).  We don't need that
hack anymore, because since commit 4b93f5799, this test case no longer
throws an error and so there's no displayed CONTEXT that could vary
depending on CLOBBER_CACHE_ALWAYS.  The underlying unstable-output
problem isn't really gone, of course, but it no longer manifests here.