Indicator lights: correct some cases where class was used

- should be translation_key, lights don't support classes

Noticed PR #2880 has copied it from somewhere, and found 3 occurrences.

custom_components/tuya_local/devices/cleverio_ap100_purifier.yaml

@@ -26,7 +26,7 @@ entities:
         name: sensor
         unit: "%"
   - entity: light
-    class: indicator
+    translation_key: indicator
     dps:
       - id: 8
         type: boolean

custom_components/tuya_local/devices/petoneer_frescomini_petfountain.yaml

@@ -11,7 +11,7 @@ entities:
         type: boolean
         name: switch
   - entity: light
-    class: indicator
+    translation_key: indicator
     category: config
     dps:
       - id: 102

custom_components/tuya_local/devices/ts106_alarm.yaml

@@ -113,7 +113,7 @@ entities:
           - dps_val: H
             value: 1.0
   - entity: light
-    class: indicator
+    translation_key: indicator
     category: config
     dps:
       - id: 122