freezer: increase timeout to 5 mins

Some apps might still be performing leftover work after being
backgrounded. Considering possible latencies due to CPU preemption, and
in the effort to reduce the impact the app freezer has on legacy apps by
allowing them to a significant grace period, extend the freezer timeout to
5 mins.

Bug: 178023335
Test: manually verified that freeze time is increased to 5 minutes
Change-Id: I74c14288a66e9a54850c0ea2b70ef3b915c2ca82