[automerger skipped] cleanup - remove send_tun() am: 73a5f20360 am: 296cdb1605 -s ours

am skip reason: Change-Id If81ca18bf5a33549b532de0d6406e32f4560c93a with SHA-1 73a5f20360 is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/android-clat/+/11736438

Change-Id: I1d8b55e2aaa2af083ab88e2b8913feaad9456e87