Remove synchronized block for test only variable am: 219d7f9275

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3377869

Change-Id: I386aed5088a62552a722dced9c14f2ce9e7544c6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>