Deflake FrameMetricsListenerTest

Sometimes the GPU duration can be zero if, for instance, a frame
dropped, or if GPU work completed so quickly it outran the estimated
start timepoint on the CPU. HWUI will try to clamp to ensure that the
GPU duration is nonnegative, but the test should allow for occasional
zero-durations.

Bug: 230713131
Test: FrameMetricsListenerTest
Change-Id: I70eee2dbbc73f22a9136ca9a09986f37c0595651
1 file changed