Set local mirror instead of mirror list in /etc/apt/sources.list

[vjr]

Currently an installation of elementary 7 horus daily results in /etc/apt/source.list having mirrorlists instead of the local archive.

This results in a poor experience during package updates/installs due to many of the mirrors being slow or out of order.

I'm located in India but I suspect these issues are relevant in many places across the globe.

Updating the build system to specify local mirrors (if possible) instead would greatly improve the experience because the requirements/guidelines for being an official country mirror from Canonical are stricter as noted here: https://wiki.ubuntu.com/Mirrors

[vjr]

I'll see if I can work on proposing a PR for this over the weekend although I am not familiar with the build options and will need to look them up.

[vjr]

On further thought, a mirrorlist may be preferable in situations such as a person carrying their laptop while traveling to different locations around the globe.

Not sure how Ubuntu handles this, if at all, because IIRC they set the archive mirror to the country mirror.

[vjr]

I was thinking of two PRs, one for the OS repo to set the mirrors value to the default "archive.ubuntu.com/ubuntu" instead of the mirrorlist and a second PR for initial-setup to prepend the two-letter country code to the /etc/apt/source.list archive entries upon selecting the language.