[skip ci] sapi/cli: Wait for the connection in Expect 100-continue abort test

The test resets the connection as soon as it is opened, so the reset could
reach the server while the connection was still in the listen backlog. The
server then never saw the request and the expected error was never logged.

Complete a request on a second connection first: the accept queue is FIFO,
so a response on the later connection means the earlier one has been
accepted, and the reset is guaranteed to hit an established connection.

Close GH-23841

Author: devnexen

sapi/cli/tests/php_cli_server_expect_100_continue_iua.phpt

@@ -11,7 +11,15 @@ if (PHP_OS_FAMILY === "Windows") die("skip SO_LINGER reset behaviour differs on
 include "php_cli_server.inc";
 $server = php_cli_server_start('echo "Hello world";', 'index.php', ['-d', 'ignore_user_abort=1']);
 
-$fp = fsockopen(PHP_CLI_SERVER_HOSTNAME, PHP_CLI_SERVER_PORT);
+$fp = php_cli_server_connect();
+
+$probe = php_cli_server_connect();
+fwrite($probe, "GET / HTTP/1.1\r\nConnection: close\r\n\r\n");
+while (!feof($probe)) {
+    fgets($probe);
+}
+fclose($probe);
+
 socket_set_option(socket_import_stream($fp), SOL_SOCKET, SO_LINGER, ['l_onoff' => 1, 'l_linger' => 0]);
 fwrite($fp, "POST / HTTP/1.1\r\nExpect: 100-continue\r\nContent-Length: 4\r\n\r\n");
 fclose($fp);