[php-src] PR #23846: ext/session: Clear in_save_handler recursion guard on bailout

Pull Request: https://github.com/php/php-src/pull/23846 Author: iliaal A zend_bailout() out of a userland save handler, a fatal error inside write() for instance, skipped the PS(in_save_handler) = 0 store in ps_call_handler(), so the flag stayed set for the rest of the request and the shutdown flush refused to call the handler, reporting "Cannot call session save handler in a recursive manner". The new test forces a real out-of-memory bailout inside write() and checks that the following write() and close() still run. bug60634_error_3.phpt and bug60634_error_4.phpt asserted the old warning and now assert the close handler running. Fixes #15529