nixos/stalwart: add fallback to /var/cache/stalwart-mail

* update test to account for fallback

nixos/modules/services/mail/stalwart.nix

@@ -154,7 +154,7 @@ in
           );
         in
         {
-          path = "/var/cache/stalwart";
+          path = if useLegacyDefault then "/var/cache/stalwart-mail" else "/var/cache/stalwart";
           resource = lib.mkIf hasHttpListener (lib.mkDefault "file://${cfg.package.webadmin}/webadmin.zip");
         };
     };

nixos/tests/stalwart/stalwart.nix

@@ -72,7 +72,7 @@ in
 
       main.succeed("test-imap-read")
 
-      main.succeed("test -d /var/cache/stalwart/STALWART_WEBADMIN")
+      main.succeed("test -d /var/cache/stalwart-mail/STALWART_WEBADMIN || test -d /var/cache/stalwart/STALWART_WEBADMIN")
       main.succeed("curl --fail http://localhost")
     '';