Update gitlab runner concurrency 1 -> 16

hive.nix

@@ -93,8 +93,12 @@ in
           };
         };
 
+        # TODO: Create module
         gitlab-runner = {
           enable = true;
+          settings = {
+            concurrent = 16;
+          };
           services = {
             nix = {
               registrationConfigFile = "/run/secrets/gitlab-runner-registration";
@@ -120,7 +124,6 @@ in
                 . ${pkgs.nix}/etc/profile.d/nix-daemon.sh
                 ${pkgs.nix}/bin/nix-channel --add https://nixos.org/channels/nixos-25.05 nixpkgs
                 ${pkgs.nix}/bin/nix-channel --update nixpkgs
-                ${pkgs.nix}/bin/nix-env -i ${pkgs.lib.concatStringsSep " " (with pkgs; [ nix cacert git openssh ])}
               '';
 
               environmentVariables = {