Remove the auto centering of dialog_shims as a experiment

Windows handles default positions better such as remembering the last position if we don't start centering it unconditionally

Fix #6032

common/dialog_shim.cpp

@@ -151,9 +151,6 @@ void DIALOG_SHIM::FinishDialogSettings()
     // SetSizeHints fixes the minimal size of sizers in the dialog
     // (SetSizeHints calls Fit(), so no need to call it)
     GetSizer()->SetSizeHints( this );
-
-    // the default position, when calling the first time the dlg
-    Center();
 }