BpfMapTest: fixes for testGetFd am: 878aae0856

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3134197

Change-Id: I37b4c2d394f9ad7685f66ad25fdf7513b018e69d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>