Disable animations during CameraMicIndicatorsPermissionTest

CameraMicIndicatorsPermissionTest waits for "idle" after back and home
button presses. In particular, it waits for the stream of accessibility
events to go quiet for at least a second.
Some apps use animations that continuously update window contents and
send window update accessibility events, preventing the stream from
going "idle".
This change disables animations during the test to remove that source of
accessibility events.

Bug: 192107479
Test: atest CameraMicIndicatorsPermissionTest
Change-Id: If17abc0b80c1a1e1b7c94675c78548c3b0c052ee