Get rid of the trusted PL/PHP
Apparently, the trusted PL/PHP has lots of security problems due to its trusted status, from sharing the same interpreter with an untrusted one, to
the fact that the trusted implementation relies on PHP safe mode, which is deprecated and allows some 'untrusted' (in PG's sense) operations, i.e. filesystem/network access. ATM we need to get rid of PL/PHP and leave only PL/PHPU implementation.