Remove vacuous tst_QLocale::cleanupTestCase()

Change-Id: I8bf9915045dce434f19de9c3745e1be28a833e8f
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

tests/auto/corelib/text/qlocale/tst_qlocale.cpp

@@ -68,7 +68,6 @@ public:
 
 private slots:
     void initTestCase();
-    void cleanupTestCase();
 #if defined(Q_OS_WIN)
     void windowsDefaultLocale();
 #endif
@@ -218,9 +217,6 @@ void tst_QLocale::initTestCase()
 #endif // QT_CONFIG(process)
 }
 
-void tst_QLocale::cleanupTestCase()
-{}
-
 void tst_QLocale::ctor()
 {
     QLocale default_locale = QLocale::system();