remove uneeded id param in context_models

tracim/models/context_models.py

         return self.content.content_id
 
     @property
-    def id(self) -> int:
-        return self.content_id
-
-    @property
     def parent_id(self) -> int:
         """
         Return parent_id of the content
         return self.revision.content_id
 
     @property
-    def id(self) -> int:
-        return self.content_id
-
-    @property
     def parent_id(self) -> int:
         """
         Return parent_id of the content