Heatstorm HS600GC: Don't hide temperature unit

Celsius setting does not seem to be being applied correctly.

From diagnostics, there does not appear to be a unit, and the temperature is
still in F, even though the device dps show a value of "c".

#1241

custom_components/tuya_local/devices/heatstorm_hs6000gc_heater.yaml

@@ -58,7 +58,6 @@ primary_entity:
     - id: 19
       type: string
       name: temperature_unit
-      hidden: true
       mapping:
         - dps_val: c
           value: C