[php-src] Issue #9981: FPM does not reset fastcgi.error_header

Issue: https://github.com/php/php-src/issues/9981 Author: bukka ### Description If fastcgi.error_header ini is set to for example "HTTP/1.1 500 Internal Server Error" and there is an error in one of the requests, the status code gets changed to the supplied value as expected. However this value is then kept for subsequent requests in the same child. That means that if the subsequent request is successful (it can be a completely different script as well), it still uses 500 status which is of course not what would users expect. ### PHP Version Tested on PHP 8.1 but likely present in PHP 7 and PHP 5 as well. ### Operating System _No response_