♻️(backend) UserSerializer fallback strategy from UserLightSerializer

In the UserLightSerializer we were fallbacking on a strategy to never
have a full_name or short_name empty. We use the part of the email
befire the @. We are doing the same thing now in the main
UserSerializer.

src/backend/core/api/serializers.py

@@ -25,22 +25,13 @@ from core.services.converter_services import (
 class UserSerializer(serializers.ModelSerializer):
     """Serialize users."""
 
-    class Meta:
-        model = models.User
-        fields = ["id", "email", "full_name", "short_name", "language"]
-        read_only_fields = ["id", "email", "full_name", "short_name"]
-
-
-class UserLightSerializer(UserSerializer):
-    """Serialize users with limited fields."""
-
     full_name = serializers.SerializerMethodField(read_only=True)
     short_name = serializers.SerializerMethodField(read_only=True)
 
     class Meta:
         model = models.User
-        fields = ["full_name", "short_name"]
-        read_only_fields = ["full_name", "short_name"]
+        fields = ["id", "email", "full_name", "short_name", "language"]
+        read_only_fields = ["id", "email", "full_name", "short_name"]
 
     def get_full_name(self, instance):
         """Return the full name of the user."""
@@ -59,6 +50,15 @@ class UserLightSerializer(UserSerializer):
         return instance.short_name
 
 
+class UserLightSerializer(UserSerializer):
+    """Serialize users with limited fields."""
+
+    class Meta:
+        model = models.User
+        fields = ["full_name", "short_name"]
+        read_only_fields = ["full_name", "short_name"]
+
+
 class TemplateAccessSerializer(serializers.ModelSerializer):
     """Serialize template accesses."""