remove wx.CENTER_ON_SCREEN and wx.CENTRE_ON_SCREEN (#12309)
We included code to add backwards compatibility for addons for the following deprecated wxPython constants wx.CENTER_ON_SCREEN = wx.CENTRE_ON_SCREEN when used with Dialog.Center()
Description of how this pull request fixes the issue:
Remove the deprecated code, and it's only usage in AskAllowUsageStatsDialog, replace with self.CentreOnScreen()
