Nixinate was causing more trouble than it saved

[noonio]

• Removes nixinate
• Now just deploy with simple nixos-rebuild commands
• Minor tidyup

This is because nixinate was giving the following error:

... Deploying nixosConfigurations.hydra-explorer from /nix/store/59q8l7cis7s6fdyq5p8k34fqn7a6p08c-source
👤 SSH User: root
🌐 SSH Host: explorer.hydra.family
🔨 Building system closure locally, copying it to remote store and activating it:
+ NIX_SSHOPTS=-t
+ /nix/store/f5c6kjnh9439gdx3ds2smjmg0fck7szq-flock-0.2.3/bin/flock -w 60 /dev/shm/nixinate-hydra-explorer /nix/store/cagvpvsk0w0crv7bg58si15mmzsf8zzs-nixos-rebuild/bin/nixos-rebuild switch --flake /nix/store/59q8l7cis7s6fdyq5p8k34fqn7a6p08c-source#hydra-explorer --target-host root@explorer.hydra.family --use-remote-sudo -s
warning: Using saved setting for 'allow-import-from-derivation = true' from ~/.local/share/nix/trusted-settings.json.
warning: Using saved setting for 'extra-substituters = https://cache.iog.io/' from ~/.local/share/nix/trusted-settings.json.
warning: Using saved setting for 'extra-trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=' from ~/.local/share/nix/trusted-settings.json.
error: unsupported tarball input attribute 'lastModified'

which wasn't a problem with the underlying command.