Chore: Remove Intl.DurationFormat polyfill from runtime (#113475)

packages/grafana-i18n/src/types/dates.d.ts

@@ -1,4 +1,4 @@
-import {
+import type {
   DurationFormatConstructor,
   DurationFormatOptions as _DurationFormatOptions,
   DurationInput as _DurationInput,

public/app/app.ts

@@ -1,7 +1,6 @@
 import 'symbol-observable';
 import 'regenerator-runtime/runtime';
 
-import '@formatjs/intl-durationformat/polyfill';
 import 'whatwg-fetch'; // fetch polyfill needed for PhantomJs rendering
 import 'file-saver';
 import 'jquery';

public/app/types/intl.d.ts

@@ -1,4 +1,4 @@
-import {
+import type {
   DurationFormatConstructor,
   DurationFormatOptions as _DurationFormatOptions,
   DurationInput as _DurationInput,