chore(NA): use core-js instead of babel-polyfill on canvas shareable runtime build

x-pack/legacy/plugins/canvas/shareable_runtime/api/index.ts

@@ -4,7 +4,8 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
+import 'core-js/stable';
+import 'regenerator-runtime/runtime';
 import 'whatwg-fetch';
-import 'babel-polyfill';
 
 export * from './shareable';