[Intrusion Logging] Bugfix: Add null check in test app

Flake in the SeucrityEventLogging tests is caused by
a missing null check in IntrusionLogging tests.

Bug: 423944078
Test: atest android.security.cts.IntrusionDetectionManagerTest
Ignore-AOSP-First: security feature
Flag: EXEMPT: bugfix for tests in localized component
Change-Id: I4073fe1d9eb1d4ec7b7af662d88900a35156de16