nixosTests.test-containers-bittorrent: enable in hydra

Now that https://github.com/NixOS/infra/pull/986 has landed, we can
enable container based tests that don't require the ability for
containers and vms to communicate.

nixos/tests/nixos-test-driver/containers.nix

@@ -2,7 +2,12 @@
 {
   name = "containers";
   meta.maintainers = with pkgs.lib.maintainers; [ jfly ];
-  # https://github.com/NixOS/infra/issues/987
+  # Relies upon /dev/net/tun, which is currently disabled in hydra due to
+  # security concerns [0].
+  # There is a PR [1] that will remove the requirement on /dev/net/tun. When/if
+  # that lands, we can run this test in hydra.
+  # [0]: https://github.com/NixOS/infra/issues/987#issuecomment-4261612652
+  # [1]: https://github.com/NixOS/nixpkgs/pull/512268
   meta.hydraPlatforms = [ ];
 
   nodes = {

nixos/tests/test-containers-bittorrent.nix

@@ -51,8 +51,6 @@ in
     maintainers = [
       lib.maintainers.kmein
     ];
-    # https://github.com/NixOS/infra/issues/987
-    hydraPlatforms = [ ];
   };
 
   containers = {