sync testem.js changes (#6529)

ui/testem.js

@@ -1,5 +1,4 @@
-/* eslint-env node */
+const config = {
-module.exports = {
   framework: 'qunit',
   test_page: 'tests/index.html?hidepassed',
   tap_quiet_logs: true,
@@ -28,3 +27,11 @@ module.exports = {
     },
   },
 };
+
+if (process.env.CI) {
+  config.reporter = 'xunit';
+  config.report_file = 'test-reports/ember.xml';
+  config.xunit_intermediate_output = true;
+}
+
+module.exports = config;