Refs #24474 -- Changed AdminSite.empty_value_display property to an attribute.

This was implemented with a property getter and setter when introduced
in 0207bdd2d4.

There is nothing special occurring here though - a simple read from and
assign to the underlying private attribute.

django/contrib/admin/sites.py

@@ -52,7 +52,7 @@ class AdminSite:
 
     enable_nav_sidebar = True
 
-    _empty_value_display = '-'
+    empty_value_display = '-'
 
     login_form = None
     index_template = None
@@ -180,14 +180,6 @@ class AdminSite:
         """
         return self._actions.items()
 
-    @property
-    def empty_value_display(self):
-        return self._empty_value_display
-
-    @empty_value_display.setter
-    def empty_value_display(self, empty_value_display):
-        self._empty_value_display = empty_value_display
-
     def has_permission(self, request):
         """
         Return True if the given HttpRequest has permission to view