nixos/release-combined: add {,latestKernel.}hardened

These now depend on an external patch set; add them to the release tests
to ensure that the build doesn't break silently as new kernel updates
are merged.

nixos/release-combined.nix

@@ -75,6 +75,7 @@ in rec {
         (onFullSupported "nixos.tests.fontconfig-default-fonts")
         (onFullSupported "nixos.tests.gnome3")
         (onFullSupported "nixos.tests.gnome3-xorg")
+        (onFullSupported "nixos.tests.hardened")
         (onSystems ["x86_64-linux"] "nixos.tests.hibernate")
         (onFullSupported "nixos.tests.i3wm")
         (onSystems ["x86_64-linux"] "nixos.tests.installer.btrfsSimple")
@@ -96,6 +97,7 @@ in rec {
         (onFullSupported "nixos.tests.keymap.dvp")
         (onFullSupported "nixos.tests.keymap.neo")
         (onFullSupported "nixos.tests.keymap.qwertz")
+        (onFullSupported "nixos.tests.latestKernel.hardened")
         (onFullSupported "nixos.tests.latestKernel.login")
         (onFullSupported "nixos.tests.lightdm")
         (onFullSupported "nixos.tests.login")