Remove spurious QTestResult::setCurrentTestData(nullptr);

Calls to QTestResult::setCurrentTestData() are handled via an RAII
class, QTestDataSetter, that ensures this final call passing nullptr
was redundant.

Change-Id: I7788e3ce898e5628d5590ef9d34182f05e85fe50
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/testlib/qtestcase.cpp

@@ -1217,7 +1217,6 @@ bool TestMethods::invokeTest(int index, const char *data, WatchDog *watchDog) co
     QTestResult::finishedCurrentTestFunction();
     QTestResult::setSkipCurrentTest(false);
     QTestResult::setBlacklistCurrentTest(false);
-    QTestResult::setCurrentTestData(nullptr);
 
     return true;
 }