ethernet: increase timeout to deflake tests am: 227dfb5ad0

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/18728707

Change-Id: I7cef17ad3bd145e03d17c082b8cea9cb5a0453ce
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>