use the new API to get all the groupIds

src/services/groups.js

@@ -320,33 +320,15 @@ class GroupService {
    * @return {Promise} Resolves to ID array.
    */
   async getGroupTreeIds(rootGroupId, maxage = 5 * 60 * 1000) {
-    //TODO: Once the fix is validated and working, remove all commented code related to caching
-    /**
-     * Removing the caching mechanism, 
-     * as the group created on the day will only be pickedup on the next day
-     * and stored in the cache
-     */
-    // const now = Date.now();
-    // const cache = this.private.cache.groupTreeIds;
 
-    /* Clean-up: removes stale records from the cache. */
-    // const CLEAN_UP_INTERVAL = 24 * 60 * 60 * 1000; // 1 day in ms.
-    // if (now - cache.lastCleanUp > CLEAN_UP_INTERVAL) {
-    //   _.forOwn(cache, ({ timestamp }, key) => {
-    //     if (now - timestamp > CLEAN_UP_INTERVAL) delete cache[key];
-    //   });
-    //   cache.lastCleanUp = now;
-    // }
+    let url = `/groups/${rootGroupId}?flattenGroupIdTree=true`;
+    const response = await this.private.api.get(url);
+    const responseJSON = handleApiResponse(response);
 
-    /* If result is found in cache, and is fresh enough, return it. */
-    // const cached = cache[rootGroupId];
-    // if (cached && now - cached.timestamp < maxage) return _.clone(cached.data);
+    const treeIds = responseJSON.flattenGroupIdTree
+    treeIds.push(rootGroupId)
 
-    /* Otherwise, fetch result from the API, write it to the cache, and
-     * finally return that. */
-    const res = reduceGroupIds(await this.getGroup(rootGroupId));
-    // cache[rootGroupId] = { data: res, timestamp: now };
-    return _.clone(res);
+    return treeIds;
   }
 
   /**