cleanup - ipv6_host_id and is_dynamic_iid

Test:
  git grep 'ipv6_host_id|is_dynamic_iid'
  comes up empty

Bug: 144730808
Test: atest clatd_test netd_integration_test
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ie3ed4583a95f15165a05412a556bae99dc07706b
3 files changed