Remove old centum tests stuff.

Remove old centum tests stuff.

Despite what the makefiles would have you believe, this was never
actually used when running the test suites. Don't ask me why - my
make-fu isn't good enough. Regardless, it's a bad idea to only
run tests for a specific set of assemblies. If some tests fail or
are unstable, they should be fixed, or disabled and have a bug
filed. Sweeping them under the rug like this is the wrong thing
to do. Incidentally, this commit doesn't add any new failures.