Disable stickers preload once in 15min

Closes #812

app/js/services.js

@@ -3682,14 +3682,9 @@ angular.module('myApp.services', ['myApp.i18n', 'izhukov.utils'])
     if (!started) {
       started = true;
       setTimeout(getStickers, 1000);
-      setInterval(preloadStickers, 900000);
     }
   }
 
-  function preloadStickers() {
-    getStickers().then(getStickersImages);
-  }
-
   function processRawStickers(stickers) {
     if (applied !== stickers.hash) {
       applied = stickers.hash;