Remove package ix as it is gone

Fails with: "error: ix has been removed from Nixpkgs, as the ix.io
pastebin has been offline since Dec. 2023".

Reviewed-by: Aleix Roca Nonell <aleix.rocanonell@bsc.es>

m/common/base/env.nix

@@ -3,7 +3,7 @@
 {
   environment.systemPackages = with pkgs; [
     vim wget git htop tmux pciutils tcpdump ripgrep nix-index nixos-option
-    nix-diff ipmitool freeipmi ethtool lm_sensors ix cmake gnumake file tree
+    nix-diff ipmitool freeipmi ethtool lm_sensors cmake gnumake file tree
     ncdu config.boot.kernelPackages.perf ldns pv
     # From bsckgs overlay
     osumb