Revert "release: Ship firmware from kmods repo on DVD"

While all of the net/wifi-firmware-*-kmod packages are in the "kmod" pkg
repository, the net/wifi-firmware-kmod metapackage itself is not; this
results in the DVD build failing when it can't fetch that.

I'm not sure if the correct fix here is to add kmod-related metapackages
to the kmod repository (even if they themselves do not contain kmods) or
something else; but this needs to be backed out at least temporarily so
that 14.4-BETA1 can happen.

This reverts commit 8c1de31097763ce1d918a3f82c61fd8d30edbe75.

This is a direct commit to releng/14.4 since it is not yet clear whether
this should be permanently removed from other branches and there is no
urgency to do so (since DVD builds are disabled by default).

With hat: re
Approved by: re (cperciva)