HLG Infinity alarm: give Learn selects a default value

Attributes are not visible when the state is unavailable, so give these
a default value so the attributes can be shown.

PR #2525

custom_components/tuya_local/devices/hlg_infinity_alarm.yaml

@@ -229,6 +229,9 @@ secondary_entities:
             value: "Panic"
           - dps_val: "CANCEL"
             value: "Cancel"
+          - dps_val: null
+            value: "Cancel"
+            hidden: true
       - id: 113
         type: integer
         name: buttons_learned
@@ -252,6 +255,9 @@ secondary_entities:
             value: "Sector 4"
           - dps_val: "CANCEL"
             value: "Cancel"
+          - dps_val: null
+            value: "Cancel"
+            hidden: true
       - id: 114
         type: integer
         name: sensors_learned