bsd.opts.mk: drop transtion aid for NO_* options

Setting NO_CTF, NO_DEBUG_FILES, NO_INSTALLLIB, NO_MAN, NO_PROFILE,
and NO_WARNS was deprecated in 2014 and made an error prior to the
13.0.0 release in commit d3a5bf95f2013af081607abd91b5175f6eafa563.
Likewise, NO_WERROR was made an error prior to 13.0.0 in commit
7fa2f2a62f04f095e1e27ad55aa22a8f59b1df8f.

Remove this transition aid making these variables no-ops as setting them
will result in an error on all supported releases.

Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D44345