test: Mark tst_controls as insignificant on Win7 + Angle

This only marks tst_controls as insignificant on Windows 7 32bit
with the Angle configuration.

Task-number: QTBUG-33029
Change-Id: I40decba840e81cb4d4b0975eb0b2da26d12d60e5
Reviewed-by: Caroline Chao <caroline.chao@digia.com>