Allow '%' again for the type in table_info() and thus tables()

It's not documented or tested in DBI, but it used to work until
DBD::Pg 3.4.0, and the change broke DBIx::Class::Schema::Loader, which
uses type='%'.

I'll separately make DBIx::Class::Schema::Loader be standad-compliant and use
undef instead of '%', but it's worth not breaking users of older versions.