user32/tests: Make failures in sysparams test less likely.
The user32:sysparams patterns page shows plenty of failures with Windows 10.
Running a single machine test did not show such a failure. Therefore the idea is there is some race condition, which shows up when testbot has more load, like in the batch runs.
While there was still a batch run active, I received with a null change the failures quite reliable.
Adding some Sleeps seems to improve the situation.
This Sleeps would add 4 seconds to each test run.