Drop graphs from dashboard that were removed in 2013

After taking some geowiki data files offline in 2013, some graphs no
longer show data; on purpose.

Since the dashboard at

  http://gp.wmflabs.org/

shows some of those blank graphs, the dashboard looks broken, although
it's showing all the data that it is supposed to show.

While we cannot bring back the data for those graphs, we at least
remove the (now) blank graphs from the dashboard, so the dashboard
looks less broken.

Bug: 72254
Change-Id: I8a6bee673401dcae3a52418687f9bef8af21980f