Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Disable the main FreeBSD pkg(7) repositories in the dvd
repository configuration to avoid fetching from upstream
in case there may be conflicts.

MFC After: 3 days
Sponsored by: The FreeBSD Foundation

Add a pkg(8) repository configuration file for cdrom-based package
installation.

As part of the 'pkg-stage' target, copy the configuration file
to the 'packages/repos/' directory on the DVD filesystem.

MFC after: 3 days
X-MFC-Before: -RC3
Sponsored by: The FreeBSD Foundation