Lower watchdog timeout for ChooserTargetService responses

Services providing direct share targets were given up to 5 seconds
to respond to a query, and for UI stability we don't show any until
all services have responded. 5 seconds is a long time to wait and
leads to user complaints when there is even one app that doesn't
respond in time.

Lower the timeout to 2 seconds as a more reasonable maximum.

Bug: 67306843
Test: manual, existing CTS
Change-Id: If55f0485240bc3ccbf8a32aa0e15903ea574ec2b