Increase timeout in testNativeWatchdogTriggersRollback

Bumps a timeout from 1 minute to 5 minutes, because in practice a lot
more needs to happen in that time window than we expect to fit in 1
minute.

Bug: 140223710
Test: atest StagedRollbackTest:com.android.tests.rollback.host.StagedRollbackTest#testNativeWatchdogTriggersRollback
Change-Id: I2a98e71102fc1cbf6ea712e070d6db49cdb05cba