[openssl/openssl] ff9728: Fix test_quic_write_read()

[Matt Caswell]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: ff9728c6d5d23ebaa73cb729c8110c0582e66280
      https://github.com/openssl/openssl/commit/ff9728c6d5d23ebaa73cb729c8110c0582e66280
  Author: Matt Caswell <matt at openssl.org>
  Date:   2023-07-10 (Mon, 10 Jul 2023)

  Changed paths:
    M test/quicapitest.c

  Log Message:
  -----------
  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 at openssl.org>
Reviewed-by: Hugo Landau <hlandau at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21409)