support/misc/Vagrantfile: reorganize provisioning

* Remove distribution upgrade cause it slows down the first boot and
  presents a bug when executed non interactively.

* Reorganize provision scripts to be in privileged and non privileged
  sections

* Add Ubuntu mirror automatic handling for apt packages sources

Fixes bug #9581

Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>