Move [[MediaWiki:bad image list]] to the beginning.
This should fix the random failing bad image tests (since
r70917?)
mentioned in [[Special:Code/MediaWiki/70938#c8458]].
They seem to be a mixture of conflict of messagecache and the internal
wfIsBadImage() cache. By always having the message in NS_MEDIAWIKI by
the time it is extracted, there shouldn't be more problems.