Move to using ssh_authorized_key type

There is a builtin type for adding authorized_keys. We started
using it for the restricted access for the puppet triggering key,
and it seems to make sense to be consistent across the board.

Change-Id: I76ffb0136c58c05fa7c8abb793cb8e3b03cb5f6c
Merge "Move to using ssh_authorized_key type"