Remove insignificant_test from DropArea test.
Remove insignificant_test from DropArea test.

The test has not been failing on recent CI runs.

Task-number: QTBUG-24588
Change-Id: I9dd29bbf1a33d9fbf042693a0995dafd887c3064
Reviewed-by: Bea Lam <3b8b412f85e38e2fbf2a7d737c89d787c51aca40@nokia.com>

matthewvogt/qtdeclarative,jfaust/qtdeclarative,crobertd/qtdeclarative,corngood/qtdeclarative,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,corngood/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,matthewvogt/qtdeclarative,qmlc/qtdeclarative,jfaust/qtdeclarative,corngood/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,mgrunditz/qtdeclarative-2d,jfaust/qtdeclarative,crobertd/qtdeclarative,matthewvogt/qtdeclarative,qmlc/qtdeclarative,qmlc/qtdeclarative,matthewvogt/qtdeclarative,crobertd/qtdeclarative,crobertd/qtdeclarative,corngood/qtdeclarative,crobertd/qtdeclarative,mgrunditz/qtdeclarative-2d,jfaust/qtdeclarative,corngood/qtdeclarative,jfaust/qtdeclarative,matthewvogt/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,matthewvogt/qtdeclarative,jfaust/qtdeclarative,crobertd/qtdeclarative,corngood/qtdeclarative,corngood/qtdeclarative,jfaust/qtdeclarative,crobertd/qtdeclarative,mgrunditz/qtdeclarative-2d,qmlc/qtdeclarative,matthewvogt/qtdeclarative