wpa_supplicant service: jobs -> systemd.services

Fixes an occurence of `jobs` usage causing tests to fail to evaluate.

thanks @domenkozar

nixos/modules/profiles/installation-device.nix

@@ -51,7 +51,7 @@ with lib;
 
     # Enable wpa_supplicant, but don't start it by default.
     networking.wireless.enable = mkDefault true;
-    jobs.wpa_supplicant.startOn = mkOverride 50 "";
+    systemd.services.wpa_supplicant.wantedBy = mkOverride 50 [];
 
     # Tell the Nix evaluator to garbage collect more aggressively.
     # This is desirable in memory-constrained environments that don't