tests: remove a useless 1 second sleep

there is no need to wait for the task to finish, it will be deleted
when the transaction is aborted anyway.

test/web/twitter_api/util_controller_test.exs

@@ -898,8 +898,6 @@ test "with credentials and valid password", %{conn: conn, user: current_user} do
         |> post("/api/pleroma/delete_account", %{"password" => "test"})
 
       assert json_response(conn, 200) == %{"status" => "success"}
-      # Wait a second for the started task to end
-      :timer.sleep(1000)
     end
   end
 end