[nixosConfig.defaultConfig] Remove unused stuff(based on perlless/bashless)

nixosModules/default-config/bootloader.nix

···
       # Should hardon and improve performance
       "page_alloc.shuffle=1"
     ];
+    # Don't use either of these so disable them
+    kexec.enable = false;
+    bcache.enable = false;
   };
 }

nixosModules/default-config/services/default.nix

···
     ./ntp.nix
     ./tailscale.nix
   ];
+  services = {
+    # Perlless user management
+    userborn = {
+      enable = true;
+    };
+  };
 }