Increase the broadcast timeout duration in the tests.

In the legacy queue, it is posssible that the broadcast
timeout is elapsed before the onApplicationAttachedLocked()
callback is received, which will result in the broadcast
receiver getting discarded.

Bug: 289108400
Test: atest services/tests/mockingservicestests/src/com/android/server/am/BroadcastQueueTest.java
Change-Id: Ic3456f0711d09a5d1e5549a326ad056bde939546