While the large data block can be written to a file, the test is
also showing instability while reading back the written block.
Adding another expected failure to address this instability.
Task-number: QTBUG-26906
Change-Id: I9704d441cf2bd6d7ef0f9023240ea61bb89561b6
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>