Remove unused wikimetrics format

Wikimetrics used to have separate formats for timeseries and
non-timeseries data.  Recurrent reports have all been standardized to
use the timeseries output format so the extra format parser is no longer
needed.

Change-Id: I7264558b8a5cf53bef281732e6d4713c08a9c526
Implement breakdowns for metrics with CSV data

Some notable steps away from Pau's original design:

 * we are graphing the different breakdowns with patterns and labels
   instead of colors
 * we are not showing the breakdowns under each language in the project
   selector
 * we turned off animation by default because performance suffered
   otherwise

The reason for these departures is that in practice the original design
was harder to implement and less performant.

Bug: T74739
Change-Id: I809d0b748d567e98174d1cb630b85546238f4d5f