Add at least one RTL language to the TestSites mock collection

When working on Wikibase/Wikidata we learned that it's always a
good idea to test with at least one right-to-left (RTL) language.
We prefer 'fa' (Farsi, the Persian language).

This change affects about 30 tests.
If they all succeed the change should be fine, right?

Change-Id: I11ded5ff98816e604da8fb92993834eb7dc99b99
Merge "Add at least one RTL language to the TestSites mock collection"