Fix Big Picture notification template test on ATV

In CTS tests we verify that notification icons are properly downscaled
to displayed sizes for memory use efficiency. In the example of Android TV, we actually show right icon in a size that is bigger than the tests resource (right notification is 640px in width, test asset was 400px in width). This prevented the resizing of the asset and caused the test to
fail.

Since we DO want to verify that drawables are downscaled on all
platforms, we're increasing the size of the test asset which will fix
failures on ATV while still verifying correct behaviour across all platforms.

Bug: 239722055
Test: forrest test runs for flame and adt3 (linked in the bug)
Change-Id: I9a6d17fd542c908bdb6e78b491a02b5d2a874a25
2 files changed