Socks5 socket engine test: Disable UDP over Socks test

... because it fails on the new network test server. The Socks5 tests
in QUdpSocket have already been disabled by commit
aa3eaf9d2ec4927df51e7d773a66f68ec5e4fce9 .

Task-number: QTBUG-35490
Change-Id: Ib062adb422ff6e5538f14d15a266d79c3bb53956
Reviewed-by: Richard J. Moore <rich@kde.org>
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>