add waitForIdle(timeout)

test item will turn on the private space mode, and this mode turns on a
large number of app operations and multiuser operations, it will be
easier for low-end devices to run in complete.

Add test waitForIdle(timeout) to make sure time execute finish.

Bug: 403200469
Test: android.app.role.cts.RoleManagerTest
#openDefaultAppListAndSetDefaultAppThenIsDefaultAppForPrivateSpace
Change-Id: I107c5a3e2c9e3fce6f68e6cefba0c6133bd547d0