Fix use of dangling pointer in ButtonTestCase::Disabled()

Fix the test added in dfec7aa0c0 which
deleted the button pointer used by EventCounter by simply moving
EventCounter initialization after the button re-creation.

See #16385.

tests/controls/buttontest.cpp

@@ -98,8 +98,6 @@ void ButtonTestCase::Click()
 
 void ButtonTestCase::Disabled()
 {
-    EventCounter clicked(m_button, wxEVT_BUTTON);
-
     wxUIActionSimulator sim;
 
     // In this test we disable the button and check events are not sent and we
@@ -118,6 +116,8 @@ void ButtonTestCase::Disabled()
         m_button->Create(wxTheApp->GetTopWindow(), wxID_ANY, "wxButton");
     }
 
+    EventCounter clicked(m_button, wxEVT_BUTTON);
+
     sim.MouseMove(m_button->GetScreenPosition() + wxPoint(10, 10));
     wxYield();