Revert "Add utilities to create IPv6 ICMP messages." am: 405c1bfca9 am: 6cc1f29354

Original change: https://android-review.googlesource.com/c/platform/frameworks/libs/net/+/1610555

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ie8c013d64b101889112e6f289f083f707773f39c