[php-src] PR #23850: ext/curl: Free the pushed handle when the push callback denies or throws

Pull Request: https://github.com/php/php-src/pull/23850 Author: iliaal When the callback denies the push, or throws and leaves the return value undefined, libcurl destroys the easy handle itself, but the wrapper kept a stale ch->cp and never released the CurlHandle it had just created, so each denied push leaked one wrapper and permanently bumped the parent's clone counter. The per-instance teardown moves out of curl_free_obj() into _php_curl_free_instance(), reused for the denied handle with ch->cp cleared first so the object dtor takes its constructor-failure exit rather than cleaning up twice. The new test needs Caddy, so it only runs in the lanes that have it.