Update valoper profile with server type

[Kouteki]

Description

We want to encourage validators to use on prem servers. For starters, let them self declare what type of server they run.

Context: https://t.me/join_gnoland/230/2853

AC

1. Add a new field for the server type (cloud/on-prem/data-center)
2. Update https://gnops.io/articles/guides/become-testnet-validator/

[Kouteki]

@sw360cab could you give access to David, so he could update the gnops article?