[DE] Add requires_context for very generic scene sentence (#3738)

* Add requires_context for very generic scene sentence

* fix: tests for licht an won't fail anymore

interestingly one of the to be failing sentences was already present in the succeeding light tests...

* fix dupliacte sentences

so... actually both sentences were present in the ligh tests already and suceeded there...

* undo bad formatting 

Refactor code to improve readability and maintainability.

Author: akloeckner

sentences/de/scene_HassTurnOn.yaml

@@ -21,6 +21,8 @@ intents:
           - "führe <name> <szene> <area> aus"
           - "<aktivieren>[ <szene>] <name> <area>"
           - "<aktivieren> <name> <szene> <area>"
+        requires_context:
+          domain: scene
         slots:
           domain: scene
         response: scene

tests/de/_test_failures.yaml

@@ -1,4 +1,2 @@
 language: de
-sentences:
-  - "Licht in der Küche an"
-  - "Licht Küche an"
+sentences: []