[php-src] PR #23464: Fix leak when iterating IntlBreakIterator parts iterators

Pull Request: https://github.com/php/php-src/pull/23464 Author: iliaal Iterating IntlBreakIterator::getPartsIterator() leaked memory on every loop because the IntlPartsIterator held a counted self-reference through its embedded zend_object_iterator's wrapping_obj, so refcount destruction could never complete, and the retained current element was additionally never released at iterator destruction. zoi_with_current_dtor() now invalidates the current element and the parts iterator leaves wrapping_obj UNDEF as the plain BreakIterator iterator already does, making teardown deterministic; the string enumeration iterator keeps its self-reference because move_forward and rewind need the owner for error handling.