folder_branch_ops: remove unused func for setting untrusted head
folder_branch_ops: remove unused func for setting untrusted head

Issue: CORE-8290

keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/kbfs,keybase/client,keybase/client,keybase/client