testing/nomad: Upgrade to 0.11.3, make nomad binary world-executable
Upgrade to 0.11.3
Also, make the nomad binary executable by anyone. As Nomad is client-server, restricting execution of the client or CLI doesn't provide security (ACLs need to be enabled on Nomad servers for that), but does make it inconvenient to use. It may even reduce security if it encourages giving root access to users who don't otherwise need it.