fix(pwa) remove no longer used file

static/pwa/registrator.js

-if ('serviceWorker' in navigator) {
-    navigator.serviceWorker
-        .register('pwa-worker.js')
-        .then(reg => {
-            console.log('Service worker registered.', reg);
-        })
-        .catch(err => {
-            console.log(err);
-        });
-}