Used fixed radii during downsampling and dynamic radii during

upsampling.

Bug:419000500
Flag: com.android.graphics.surfaceflinger.flags.window_blur_kawase2
Test: Run battery and jank suites with this patch and observe impact.
Test: Pull shade down and observe blur during transition.

Change-Id: I7e4552d0d4fc354d7ed440e6762dc3b8d1856f66