fix nextcloud (case when enabled)

Previously, second mkIf for cleanup case took precedence when merge with
`//`. Now it's 2 modules: one for selfprivacy.modules.nextcloud.enable
== true, another for selfprivacy.modules.nextcloud.enable == false.

sp-modules/nextcloud/flake.nix

@@ -2,7 +2,8 @@
   description = "PoC SP module for nextcloud";
 
   outputs = { self }: {
-    nixosModules.default = import ./module.nix;
+    nixosModules.default = _:
+      { imports = [ ./module.nix ./cleanup-module.nix ]; };
     configPathsNeeded =
       builtins.fromJSON (builtins.readFile ./config-paths-needed.json);
   };