[BUGFIX] Remove unused async in tests.

3.12+ transpile `async` / `await` in tests without issue, but 3.10 and
lower do not. This stray (and unused!) `async` slipped through via a
cherry-pick and caused IE11 test suite to fail (and therefore prevented
publishing of 3.10.2).

packages/@ember/-internals/glimmer/tests/integration/components/link-to/query-params-angle-test.js

@@ -280,7 +280,7 @@ if (EMBER_GLIMMER_ANGLE_BRACKET_BUILT_INS) {
         );
 
         return this.visit('/')
-          .then(async () => {
+          .then(() => {
             assert.equal(this.$('#good-link').length, 1, 'good-link should be in the DOM');
             assert.equal(this.$('#bad-link').length, 1, 'bad-link should be in the DOM');