caroot: properly remove old distrusted roots

caroot: properly remove old distrusted roots

The proper procedure was not followed in r364943; all of these that were
deleted should have instead been moved over to the blacklist so that certctl
can DTRT.

Users must still `certctl rehash` after this, but this should generally be
done by one of mergemaster/etcupdate/freebsd-update/pkgbase already; note
that freebsd-update doesn't come into play for this particular update, as
these have not yet made it into a release.

Future work (after svn -> git) will likely change the script that updatecert
invokes to facilitate the process, rather than trusting that kevans or
whomever updates in the future will remember.

Reported by:	Helge Oldach <freebsd oldach net>
MFC after:	3 days