Resolve #2897638: "Views exposed sort identifiers are not configurable"

Closes #2897638

core/modules/comment/config/optional/views.view.comment.yml

@@ -806,6 +806,7 @@ display:
           exposed: false
           expose:
             label: ''
+            field_identifier: changed
           granularity: second
           entity_type: comment
           entity_field: changed