Increase frame limit for bubble bar screen test

This test is flaky because the animation sometimes doesn't
finish before the screenshot is taken. Increasing the frame
limit should help to ensure that the animation has time to
finish.

ABTD 100x runs (passed): https://android-build.corp.google.com/abtd/run/L84400030006722716

Change-Id: I410fb74a947d805551ce1b2303f0dc4c8d616de9
Flag: com.android.wm.shell.enable_bubble_bar
Fixes: 366544536
Test: ABTD above