tests/unit/test-util-sockets: Remove temporary file after test

tests/unit/test-util-sockets: Remove temporary file after test

test-util-sockets leaves the temporary socket files around in the
temporary files folder. Let's better remove them at the end of the
testing.

Fixes: 4d3a329af5 ("tests/util-sockets: add abstract unix socket cases")
Message-ID: <20240226082728.249753-1-thuth@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
(cherry picked from commit f0cb6828ae34fb56fbb869bb3147a636d1c984ce)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>