Cleanup to our stat scripts

Removed lots of separate shell scripts in favour of
standardizing the logic in one place.

Plans for later:
* Generate second table of subgroups for projects that
  have those.
* In case unwanted languages start appearing in the tables,
  use the language list provided by the message group.

Change-Id: I6eb7a856897d816182e8a703c83ffae260a81ff8
Merge "Cleanup to our stat scripts"