arr-init: fix prowlarr health check failure

Disable health checks on Prowlarr -- the synced-app testall endpoint
requires Sonarr/Radarr to reverse-connect to prowlarrUrl, which is
unreachable across the wg namespace boundary.

Also add networkNamespaceService = "wg" for the new configurable
namespace service dependency (replaces old hardcoded wg.service).

services/arr/init.nix

@@ -8,7 +8,10 @@
       dataDir = service_configs.prowlarr.dataDir;
       apiVersion = "v1";
       networkNamespacePath = "/run/netns/wg";
-      healthChecks = true;
+      networkNamespaceService = "wg";
+      # Synced-app health checks require Sonarr/Radarr to reverse-connect to
+      # prowlarrUrl, which is unreachable across the wg namespace boundary.
+      healthChecks = false;
       syncedApps = [
         {
           name = "Sonarr";