ethernet: remove EthernetManager shims am: f8d403cb4a

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/18728987

Change-Id: I168632b17a4a3b0565af1e9ed694c1489acf3c5b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>