[mob][photos] Show loading indicator till the image of face in face filter is ready

mobile/lib/ui/viewer/hierarchicial_search/filter_chip.dart

@@ -102,6 +102,7 @@ class FaceFilterChip extends StatelessWidget {
                     faceThumbnailFile,
                     personId: personId,
                     clusterID: clusterId,
+                    thumbnailFallback: false,
                   ),
                 ),
               ),

mobile/lib/ui/viewer/search/result/person_face_widget.dart

@@ -8,6 +8,7 @@ import 'package:photos/models/file/file.dart';
 import "package:photos/models/ml/face/face.dart";
 import "package:photos/models/ml/face/person.dart";
 import "package:photos/services/machine_learning/face_ml/person/person_service.dart";
+import "package:photos/theme/ente_theme.dart";
 import "package:photos/ui/common/loading_widget.dart";
 import "package:photos/ui/viewer/file/thumbnail_widget.dart";
 import "package:photos/utils/face/face_box_crop.dart";
@@ -70,7 +71,9 @@ class PersonFaceWidget extends StatelessWidget {
           }
           return thumbnailFallback
               ? ThumbnailWidget(file)
-              : const EnteLoadingWidget();
+              : EnteLoadingWidget(
+                  color: getEnteColorScheme(context).fillMuted,
+                );
         }
       },
     );