bsdconfig: Change DNS name for HTTP main dist

[dteske]

Test Plan

Functionally these URLs are the same, but this is less confusing

[dteske]

Turns out they only look similar. download forwards to HTTPS and http://ftp.freebsd.org/ also has a different structure to access the data. For example, on download, the releases are in /ftp/releases/ while on http://ftp.freebsd.org/ the releases are in /pub/FreeBSD/releases/

Additional changes will be required to switch over from ftp to download for the HTTP access.

It would be nice if we could have bsdconfig use download.freebsd.org for both FTP and HTTP access, but to further confuse matters, paths like /pub/FreeBSD/releases/ work the same regardless of whether you use ftp.freebsd.org vs download.freebsd.org when you login via FTP -- it's only over HTTP that they disagree with respect to paths (making a request for /pub/FreeBSD/releases/ over HTTP to download.freebsd.org will result in 404 Not Found whereas making a request for the same path over HTTP to ftp.freebsd.org or over FTP to either ftp.f.o or download.f.o all succeed).

Perhaps the solution is not to modify bsdconfig but to change download.freebsd.org HTTP server to provide a path structure that emulates the other 3, providing /pub/FreeBSD/releases/ and other /pub/FreeBSD/* at minimum.