tested job: fix evaluation of chromium tests

It's a bit inconsistent now, but I want mainly unblock the channel.
/cc maintainer @aszlig.

nixos/release-combined.nix

@@ -48,7 +48,7 @@ in rec {
         nixos.ova.x86_64-linux
 
         #(all nixos.tests.containers)
-        (all nixos.tests.chromium)
+        nixos.tests.chromium
         (all nixos.tests.firefox)
         (all nixos.tests.firewall)
         nixos.tests.gnome3.x86_64-linux # FIXME: i686-linux