Clear calling identity before verifying listeners

Also don't throw when can't verify listener.

And update mocking in tests to clean state between tests.

Bug: 36783632
Fixes: 37263567
Test: runtest-systemui-notification, create a secondary user
Change-Id: I5ec95539c9859b67b8fbc7e6a85334e08e6b5a98
2 files changed