tests/qtest: migration-test: Enable TLS PSK tests for win32

Since commit f1018ea0 ("tests: avoid DOS line endings in PSK file"),
the bug of the helper test_tls_psk_init_common() that caused TLS PSK
tests to fail on Windows was fixed. Let's enable these tests on win32.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Message-Id: <20221101035021.729669-1-bin.meng@windriver.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>