Remove ./diff directory and contents for two tests.

The ./diff directory exists to test specific features of patch systems when upstream sources that that are unpackaged when building a debian patch differ from contents in a nearby orig.tar.gz tarfile. In the present cases, the contents of the ./diff directories are identical to that of ./orig. Thus, there are no differences. Also, neither test seems to exercise a potential false positive related to the feature. Both ./diff directories are removed.