Add timeout logic to TestWakeupClientServiceImpl.

Add timeout logic for fake tasks. They will timeout after 20s and
print an error message if not received by the remote access HAL.

Test: Manually run TestWakeupClientServiceImpl and verify the log:
Task for client ID: [ID] timed-out
is printed.
Bug: 246841306

Change-Id: I2173c931da9e0ea40c7b16f9e25a75592fa255c0