[php-src] Issue #23425: sapi_cli_server_send_headers does not check return value of php_cli_server_client_send_through

Issue: https://github.com/php/php-src/issues/23425
Author: Sjord

### Description

php_cli_server_client_send_through can fail without bailing out, if ignore_user_abort=1. sapi_cli_server_send_headers then fails, but it returns SAPI_HEADER_SENT_SUCCESSFULLY.

In sapi/cli/php_cli_server.c:

```
	php_cli_server_client_send_through(client, ZSTR_VAL(buffer.s), ZSTR_LEN(buffer.s));

	smart_str_free(&buffer);
	return SAPI_HEADER_SENT_SUCCESSFULLY;
}
```

### PHP Version

```plain
master
```

### Operating System

_No response_