tst_QNetworkReply: fix mis-guided use of QSKIP().

QSKIP() causes the whole test to be skipped, where this work-around
for a known quirk of the test server only requires skipping a single
Q_COMPARE(); the rest of the test passes fine without it.

Change-Id: Ie4612bd428f4cb4b342fad908cc2784fbadf069c
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@theqtcompany.com>