update jj and add auto-gc for boot

apps/nogui/jj.nix

@@ -20,7 +20,7 @@
       };
       git.push-bookmark-prefix = "change/";
       signing = {
-        sign-all = true;
+        behavior = "own";
         backend = "ssh";
         key = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIAUxLwkJOlalAHTdkbh+m49XTZGKDqWz1o/o8OLmtQdX";
       };

machines/common/nogui/default.nix

@@ -43,7 +43,11 @@
   nixpkgs.config.allowUnfree = true;
 
   nix = {
-    gc.automatic = true;
+    gc = {
+      automatic = true;
+      randomizedDelaySec = "15m";
+      options = [ "--delete-older-than 14d" ];
+    };
     optimise.automatic = true;
     package = pkgs.nixVersions.stable;
     settings = {