Fix test_quic_write_read()

Fix the "test 2" case of test_quic_write_read(). It is intended to be run
in blocking mode.

The result of a bad interaction between #21087 and #21332

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #21409)

test/quicapitest.c

@@ -60,7 +60,7 @@ static int test_quic_write_read(int idx)
 
     if (!TEST_ptr(cctx)
             || !TEST_true(qtest_create_quic_objects(libctx, cctx, cert, privkey,
-                                                    idx == 1 ? QTEST_FLAG_BLOCK : 0,
+                                                    idx >= 1 ? QTEST_FLAG_BLOCK : 0,
                                                     &qtserv, &clientquic, NULL))
             || !TEST_true(SSL_set_tlsext_host_name(clientquic, "localhost"))
             || !TEST_true(qtest_create_quic_connection(qtserv, clientquic)))