[mob][photos] Remove redundant clustering code

mobile/lib/services/machine_learning/face_ml/face_clustering/clusters_mapping.dart

@@ -1,22 +0,0 @@
-import "package:photos/face/model/person.dart";
-
-enum MappingSource {
-  local,
-  remote,
-}
-
-class ClustersMapping {
-  final Map<int, Set<int>> fileIDToClusterIDs;
-  final Map<int, String> clusterToPersonID;
-  // personIDToPerson is a map of personID to PersonEntity, and it's same for
-  // both local and remote sources
-  final Map<String, PersonEntity> personIDToPerson;
-  final MappingSource source;
-
-  ClustersMapping({
-    required this.fileIDToClusterIDs,
-    required this.clusterToPersonID,
-    required this.personIDToPerson,
-    required this.source,
-  });
-}

mobile/lib/services/machine_learning/face_ml/face_clustering/cosine_distance.dart

@@ -67,11 +67,3 @@ double cosineDistForNormVectors(List<double> vector1, List<double> vector2) {
   }
   return 1.0 - dotProduct;
 }
-
-double calculateSqrDistance(List<double> v1, List<double> v2) {
-  double sum = 0;
-  for (int i = 0; i < v1.length; i++) {
-    sum += (v1[i] - v2[i]) * (v1[i] - v2[i]);
-  }
-  return sqrt(sum);
-}