Make sitelink browsertests work on beta labs

- the instances on beta labs provide limited content
  e.g. there are only a few wikipedias and those only have
  a limited number of articles. this needs to be taken into account
  when choosing testcases. an alternative would be to implement a
  better setup logic, e.g. create new articles on the beta wikipedias
  before running sitelinks tests.

Change-Id: If8eff8824456470253b7172c41e1b45585b396ed
Merge "Make sitelink browsertests work on beta labs"