Add pagination for dashboard and user activity feeds (#22937)

Previously only the last few activities where available. This works for
all activity and for activity on a date chosen on the heatmap.

web_src/js/components/ActivityHeatmap.vue

@@ -70,6 +70,8 @@ export default {
         params.set('date', clickedDate);
       }
 
+      params.delete('page');
+
       const newSearch = params.toString();
       window.location.search = newSearch.length ? `?${newSearch}` : '';
     }