tst_QPropertyAnimation::noStartValue() is flakey

Sometimes tst_QPropertyAnimation::noStartValue() fails without no real reason. Same test is succeed after re-try so this cause instability in our systems and should be fixed.

From the log (no better log available atm, sorry):

FAIL!  : tst_QPropertyAnimation::noStartValue() Compared values are not the same
    Actual   (o.values.last()): 409
    Expected (420)            : 420