fix: remove sourceMaps false in ember-cli-build

There was previously a bug with sourceMaps that slowed down the build.
This issue has been resolved by Ember and now we can expect the default
behavior of sourceMaps being enabled in dev and disabled in prod.

ui/ember-cli-build.js

@@ -31,9 +31,6 @@ module.exports = function (defaults) {
     },
     hinting: isTest,
     tests: isTest,
-    sourcemaps: {
-      enabled: false,
-    },
   });
 
   // Use `app.import` to add additional libraries to the generated