Domain IP check not reliable

#### Steps to reproduce the issue
- Use latest VVV to share a host on a public IP
- Try to connect

#### What I expected
- Connection works

#### What happened instead
- Error like "Domain `my.vvv.site.vagrant.com` just failed is_usable_domain check as its IP `127.0.0.1` is either invalid, or in a reserved or private range."

This is happening because Vagrant resolves the public domain to 127.0.0.1 on the server, but it still has a valid public IP as well. Connecting should work. We should rely on WordPress.com to tell us if a domain can be resolved to a public IP or not.

No file or test is named in the issue. Reproduce the VVV setup with a host on a public IP and trace the domain usability check that rejects 127.0.0.1. Done means the connection works and WordPress.com determines whether the domain resolves to a public IP.

Written by the indexing model from the issue text.