Exclude translation caused by surface insets from the matrix

The matrix returned from getTransformationMatrix is used by a11y
controller for computing the touchable region. Since the touchable
region doesn't include the surface insets area, the translation in the
method should not be affected by surface insets.

Fix: 151868913
Test: atest WindowStateTests
Change-Id: I1ae58716d7270a58d527b807b74cdadc6e4624ab