fix: align private and channel update semantics

(cherry picked from commit c65f76f56278f74082c4fa792ed49104d5d33c38)

deploy/migrations/0068_content_unread_and_blocks.down.sql

@@ -0,0 +1,35 @@
+DROP TABLE IF EXISTS contact_blocks;
+
+ALTER TABLE user_update_events
+    DROP CONSTRAINT IF EXISTS user_update_events_type_check;
+
+ALTER TABLE user_update_events
+    ADD CONSTRAINT user_update_events_type_check CHECK (
+        event_type IN (
+            'new_message',
+            'read_history_inbox',
+            'read_history_outbox',
+            'edit_message',
+            'message_reactions',
+            'contacts_reset',
+            'dialog_pinned',
+            'pinned_dialogs',
+            'dialog_unread_mark',
+            'peer_settings',
+            'delete_messages',
+            'dialog_filter',
+            'dialog_filter_order',
+            'dialog_filters',
+            'folder_peers',
+            'channel_available_messages',
+            'channel_view_forum_as_messages',
+            'noop'
+        )
+    );
+
+ALTER TABLE channel_unread_mentions
+    DROP COLUMN IF EXISTS media_unread;
+
+ALTER TABLE message_boxes
+    DROP COLUMN IF EXISTS reaction_unread,
+    DROP COLUMN IF EXISTS media_unread;