Increase timeout of ActivityMetricsLaunchObserverTests

The test is flaky due to the message is not handled in a short time.
Especially the testing device may not be fast and there could have
other messages in the queue, e.g. in setUpAMLO, registerLaunchObserver
also sends message to the same handler.

Bug: 129138370
Test: atest ActivityMetricsLaunchObserverTests
Change-Id: I67a1d3bb1e0efb014cd443e84313d1a90010ac4c