Installing a package created by makefontpkg throws errors on installation

Due to #6 and #7, which removed the dependencies, the calls to mkfontscale and mkfontdir now fail.

As they seem to be unneccesary (they are done by pacman hooks anyway if the packages are installed), the calls can be removed. In my case fc-cache was installed already (via `fontconfig`) but as there is no dependency, even that call will fail. (See the [guidelines](https://wiki.archlinux.org/title/Font_package_guidelines#Dependencies)).

As the hooks already take care of everything, I think it's fine to remove all pre/post install/update/etc functions/scripts of this package(=the .INSTALL file).