Restructure flake.nix for a simpler config for building different images off the same NixOS config.

nix/configuration/roles/qemu/default.nix

@@ -52,14 +52,10 @@ in
     };
   };
 
-  config = lib.mkIf config.me.qemu.enable (
-    lib.mkMerge [
-      {
-        environment.systemPackages = with pkgs; [
-          qemu
-          qemurc_wrapped
-        ];
-      }
-    ]
-  );
+  config = lib.mkIf config.me.qemu.enable {
+    environment.systemPackages = with pkgs; [
+      qemu
+      qemurc_wrapped
+    ];
+  };
 }