Fix course page when switching to a different language

- Include language-configurations.language.leaderboard in course route
  load so the right sidebar can show the leaderboard for the selected
  language without triggering an unloaded-relationship error.
- Do not clear activeRepositoryOverride after saving a language
  selection so the UI and leaderboard stay on the newly saved repo
  instead of reverting to the stale model.activeRepository.

Author: VasylMarchuk

app/controllers/course.ts

@@ -133,7 +133,7 @@ export default class CourseController extends Controller {
 
     this.repo = this.activeRepository.id;
     this.track = undefined;
-    this.activeRepositoryOverride = null;
+    // Keep activeRepositoryOverride so we keep showing this repo (model never refreshes)
 
     return true;
   }

app/routes/course.ts

@@ -98,7 +98,7 @@ export default class CourseRoute extends BaseRoute {
     const includedCourseResources = [
       'extensions',
       'stages.solutions.language',
-      'language-configurations.language',
+      'language-configurations.language.leaderboard',
       'stages.screencasts',
       'stages.screencasts.language',
       'stages.screencasts.user',

app/routes/course/stage.ts

@@ -19,10 +19,7 @@ export default class CourseStageRoute extends BaseRoute {
     super(...args);
 
     this.router.on('routeDidChange', (transition: Transition) => {
-      if (
-        transition?.from?.name === 'course.introduction' &&
-        transition?.to?.name === 'course.introduction'
-      ) {
+      if (transition?.from?.name === 'course.introduction' && transition?.to?.name === 'course.introduction') {
         return;
       }