[NOP] removed dead code

The DateFormatFileAppender got orphaned with commit
8027056d0f897bc93319a70e3625639e9122ddae that removed it from the
log4j configuration file.

Change-Id: I5d4a011968511d2accf794e93078b49dd85360ac
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1403
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>