test: detects parent setUp not being called

test: detects parent setUp not being called

Our test classes often overload MediaWikiTestCase::setUp() but forget to
call their parent. This patch makes MediaWikiTestCase to flag whenever
its own setUp() is called and then simply assert it got called. Any
class failing the assertion is missing a call to its parent setup which
is easily fixed by adding: parent::setUp().

It would be nice to find a similar trick for tearDown().

Change-Id: Ia2afed6052eb3863d6c8e68c551cf03b33bb4be9