Removed placeholder prefix

app/src/main/java/org/schabi/newpipe/util/ServiceHelper.java

@@ -33,7 +33,7 @@ public final class ServiceHelper {
             case 0:
                 return R.drawable.ic_smart_display;
             case 1:
-                return R.drawable.ic_placeholder_cloud;
+                return R.drawable.ic_cloud;
             case 2:
                 return R.drawable.ic_placeholder_media_ccc;
             case 3:
@@ -41,7 +41,7 @@ public final class ServiceHelper {
             case 4:
                 return R.drawable.ic_placeholder_bandcamp;
             default:
-                return R.drawable.ic_placeholder_circle;
+                return R.drawable.ic_circle;
         }
     }