cleanup - ipv6_host_id and is_dynamic_iid am: 2f45839780 am: 9f68dda9b6

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/android-clat/+/11735696

Change-Id: Ic655db4c6c64c3a5081620bb3ad523fa9dc7d7f5