* Improve how we set 'proxy=' in yum.conf or dnf.conf

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

* Fixup spaces in no_proxy

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>

* Add svc,svc.{{ dns_domain }} to no_proxy

Signed-off-by: Etienne Champetier <champetier.etienne@gmail.com>