Fix flaky test AccessibilityEmbeddedDisplayTest

Give fixed size for ActivityView may cause it over boundary in some
situations (e.g., small screen and landscape mode). Use match parent
instead of fixed size since this test focus on resizing.

Bug: 128440387
Test: atest AccessibilityEmbeddedDisplayTest
Change-Id: I3d3063885bab239b4073379117e051c36d3cf92c
1 file changed