Redhat: remove perl-{DBI,DBD-MySQL} dependency

This dependency is needed for mysqlhotcopy, which we aren't intending
to use. We are removing it because perl-DBD-MySQL is a separate package
that depends on libmysqlclient.so, which is versioned. We would have to
rebuild *this* in order to use mysql-server, which I can't be bothered
to do.