Add User.decrease_note_count and call it from ActivityPub.delete

test/user_test.exs

@@ -296,6 +296,25 @@ defmodule Pleroma.UserTest do
       assert user.info["note_count"] == 2
     end
 
+    test "it decreases the info->note_count property" do
+      note = insert(:note)
+      user = User.get_by_ap_id(note.data["actor"])
+
+      assert user.info["note_count"] == nil
+
+      {:ok, user} = User.increase_note_count(user)
+
+      assert user.info["note_count"] == 1
+
+      {:ok, user} = User.decrease_note_count(user)
+
+      assert user.info["note_count"] == 0
+
+      {:ok, user} = User.decrease_note_count(user)
+
+      assert user.info["note_count"] == 0
+    end
+
     test "it sets the info->follower_count property" do
       user = insert(:user)
       follower = insert(:user)