Resolve TODO in gr-rest-api-mock.

Unfortunately, this leads to a race-condition in
service-worker-installer_test.ts

Added a TODO there to fix this.

Release-Notes: skip
Change-Id: I26a3738d43c38c44ec24fb107342c6c3e93f94f2

polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts

diff --git a/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts b/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
index d7a842a..cd0c2dd 100644
--- a/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
+++ b/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
@@ -68,13 +68,13 @@
   createCommit,
   createConfig,
   createMergeable,
-  createPreferences,
   createServerInfo,
   createSubmittedTogetherInfo,
 } from '../test-data-generators';
 import {
   createDefaultDiffPrefs,
   createDefaultEditPrefs,
+  createDefaultPreferences,
 } from '../../constants/constants';
 import {ParsedChangeInfo} from '../../types/types';
 import {getBaseUrl} from '../../utils/url-util';
@@ -381,8 +381,7 @@
     return Promise.resolve({});
   },
   getPreferences(): Promise<PreferencesInfo | undefined> {
-    // TODO: Use createDefaultPreferences() instead.
-    return Promise.resolve(createPreferences());
+    return Promise.resolve(createDefaultPreferences());
   },
   getProjectConfig(): Promise<ConfigInfo | undefined> {
     return Promise.resolve(createConfig());