fix(tours): open the tour dialogs in the middle of the screen

The walk from a Google Maps link, the take-over from another trip and the
other new tour dialogs sat at the top of the screen; they now open centred
like the planner's own dialogs.

client/src/components/Atlas/tourActivity/TourActivityStatsDialog.tsx

@@ -151,7 +151,6 @@ export function TourActivityStatsDialog({
       onClose={onClose}
       labelledBy={labelId}
       width="editor"
-      align="top"
       header={
         <DialogHeader
           tile={