IpSecManagerTest: clean up assertion for better error reporting am: a1e4289eeb

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2592285

Change-Id: I0ff13b875c2c44df087e82d75394c514a89a1801
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>