[php-src] PR #23860: Revert "Backport: reject cURL callback changes from callbacks (#23814)"

Pull Request: https://github.com/php/php-src/pull/23860 Author: nicolas-grekas This reverts d82f1ff50f9, the backport of #23814 to PHP-8.4, and to PHP-8.5 through the merge-up. The new Error breaks code that worked: Symfony's HttpClient replaces its CURLOPT_WRITEFUNCTION from within the write callback, a closure, which the UAF doesn't affect. With the backport, every response with a body fails. That's fine for 8.6, not for a patch release, see https://github.com/php/php-src/pull/23814#issuecomment-5791503105 PHP-8.6 and master should keep the change, so the merge-up into PHP-8.6 needs to keep 8.6's side. If the UAF has to be fixed on 8.4 and 8.5, keeping the previous callback alive until it returns would do it without rejecting the call.