Fix MediaWikiPageLinkRendererTest failing in non-English setups

An other test that just assumes the testing environment is an English
MediaWiki. A very easy and hopefully very obvious fix. This even
restores the original content language.

Change-Id: I1c303e0f42465a95540cc093a0ff4bfb0180c686
Merge "Fix MediaWikiPageLinkRendererTest failing in non-English setups"