Remove netctl

netctl isn't required since v2.2.10, but we need to wait for the slow updating distro (Debian, CentOS etc.), before we can remove it.

https://github.com/hashicorp/vagrant/pull/11400

changed due date to June 01, 2021

I set a due date to remind us to remove this in a few months.

@klausenbusk so is it time to nuke this? We've reached the deadline.

closed with commit 5ca90361