nixos/tests/kde5: rename from sddm-kde5 and run by default

(cherry picked from commit 701f02a6eed902835e3d2a27838723cd9a7bb66a)

nixos/release-combined.nix

@@ -73,6 +73,7 @@ in rec {
         (all nixos.tests.ipv6)
         (all nixos.tests.i3wm)
         (all nixos.tests.kde4)
+        (all nixos.tests.kde5)
         #(all nixos.tests.lightdm)
         (all nixos.tests.login)
         (all nixos.tests.misc)

nixos/release.nix

@@ -251,6 +251,7 @@ in rec {
   tests.ipv6 = callTest tests/ipv6.nix {};
   tests.jenkins = callTest tests/jenkins.nix {};
   tests.kde4 = callTest tests/kde4.nix {};
+  tests.kde5 = callTest tests/kde5.nix {};
   tests.keymap = callSubTests tests/keymap.nix {};
   tests.initrdNetwork = callTest tests/initrd-network.nix {};
   tests.kubernetes = hydraJob (import tests/kubernetes.nix { system = "x86_64-linux"; });
@@ -284,7 +285,6 @@ in rec {
   tests.quake3 = callTest tests/quake3.nix {};
   tests.runInMachine = callTest tests/run-in-machine.nix {};
   tests.sddm = callTest tests/sddm.nix {};
-  tests.sddm-kde5 = callTest tests/sddm-kde5.nix {};
   tests.simple = callTest tests/simple.nix {};
   tests.smokeping = callTest tests/smokeping.nix {};
   tests.taskserver = callTest tests/taskserver.nix {};