fix(frontends/lean/info_manager): disable notation pretty printer when displaying `OVERLOAD` information

We need that otherwise the Lean emacs mode will display useless overload
information such as:

            [+] int.add : ℤ → ℤ → ℤ
            overloaded with #1 + #0, #1 + #0

Note that this only became an issue after we implemented the new pretty printer