Remove more code so that double-clicking on a file (in double-click mode) doesn't select the file + the dir + the dir again, in KFile::Files | KFile::Directory mode.

The activated() signal is indeed enough, no need to do anything about double-click explicitely anywhere.

Tested with the "bug 173137" testcase in kfiledialogtest, in single-click and double-click mode, and testing with click + Ok, Key_Enter, double-click. Hope I didn't miss anything.

The bug was already marked as fixed, but double-click global setting was probably not tested back then.
Reported by xdarklight.