Remove unused import from EthernetTetheringTestBase am: f093d22fcc am: 8bcc146b77

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3140837

Change-Id: I846a39a2768fb211b8fba99605c3a089859db171
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>