MOBILE-3401: Remove duplicated code from course provider

Author: NoelDeMartin

src/core/course/providers/course.ts

@@ -31,8 +31,6 @@ import { CorePushNotificationsProvider } from '@core/pushnotifications/providers
 import { CoreCoursesProvider } from '@core/courses/providers/courses';
 import { makeSingleton } from '@singletons/core.singletons';
 
-import { makeSingleton } from '@singletons/core.singletons';
-
 /**
  * Service that provides some features regarding a course.
  */
@@ -1164,8 +1162,6 @@ export class CoreCourseProvider {
     }
 }
 
-export class CoreCourse extends makeSingleton(CoreCourseProvider) {}
-
 /**
  * Data returned by course_summary_exporter.
  */