Change interlanguage link title message key

The term or abbreviation "iwiki" doesn't exist and has no meaning in
MediaWiki.

Bug: 56129
Change-Id: I0796b897e9646c122a46de449aaabf4d7a867f00
(cherry picked from commit d5aac9f6e001dfe11f3b6e67bb7cb24dbbb224ff)