Remove unnecessary changes and follow conventions

mobile/lib/widgets/common/immich_thumbnail.dart

@@ -13,20 +13,12 @@ import 'package:octo_image/octo_image.dart';
 import 'package:immich_mobile/providers/user.provider.dart';
 
 class ImmichThumbnail extends HookConsumerWidget {
-  const ImmichThumbnail({
-    this.asset,
-    this.width = 250,
-    this.height = 250,
-    this.fit = BoxFit.cover,
-    super.key,
-    this.placeholderEnabled = true,
-  });
+  const ImmichThumbnail({this.asset, this.width = 250, this.height = 250, this.fit = BoxFit.cover, super.key});
 
   final Asset? asset;
   final double width;
   final double height;
   final BoxFit fit;
-  final bool placeholderEnabled;
 
   /// Helper function to return the image provider for the asset thumbnail
   /// either by using the asset ID or the asset itself
@@ -55,7 +47,7 @@ class ImmichThumbnail extends HookConsumerWidget {
 
     if (asset == null) {
       return Container(
-        color: Colors.black,
+        color: Colors.grey,
         width: width,
         height: height,
         child: const Center(child: Icon(Icons.no_photography)),