Core: Move VcsManager test class definition closer to tested code

Change-Id: Ibc97d4874eca871d7d283dc97bf61235e9ea5539
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/coreplugin.h

@@ -62,8 +62,6 @@ public slots:
 
 #if defined(WITH_TESTS)
 private slots:
-    void testVcsManager_data();
-    void testVcsManager();
     // Locator:
     void test_basefilefilter();
     void test_basefilefilter_data();