release-combined: readd keymap tests

These are building just fine for a while now [0].
I restricted them from bulding on aarch64-linux because
there's still issues there.

[0]: https://hydra.nixos.org/job/nixos/trunk-combined/nixos.tests.keymap.dvorak.x86_64-linux/all

nixos/release-combined.nix

@@ -95,14 +95,12 @@ in rec {
         (all nixos.tests.env)
         (all nixos.tests.ipv6)
         (all nixos.tests.i3wm)
-        # 2018-06-06: keymap tests temporarily removed from tested job
-        # since non-deterministic failure are blocking the channel (#41538)
-        #(all nixos.tests.keymap.azerty)
-        #(all nixos.tests.keymap.colemak)
-        #(all nixos.tests.keymap.dvorak)
-        #(all nixos.tests.keymap.dvp)
-        #(all nixos.tests.keymap.neo)
-        #(all nixos.tests.keymap.qwertz)
+        (except ["aarch64-linux"] nixos.tests.keymap.azerty)
+        (except ["aarch64-linux"] nixos.tests.keymap.colemak)
+        (except ["aarch64-linux"] nixos.tests.keymap.dvorak)
+        (except ["aarch64-linux"] nixos.tests.keymap.dvp)
+        (except ["aarch64-linux"] nixos.tests.keymap.neo)
+        (except ["aarch64-linux"] nixos.tests.keymap.qwertz)
         (all nixos.tests.plasma5)
         (all nixos.tests.lightdm)
         (all nixos.tests.login)