Avoid string decode/encode round trip in websocket_api get_services (#108632)

The cache was converting from bytes to str and when we read
the cache we converted it back to bytes again

homeassistant/components/websocket_api/commands.py

@@ -45,7 +45,7 @@ from homeassistant.helpers.json import (
     JSON_DUMP,
     ExtendedJSONEncoder,
     find_paths_unserializable_data,
-    json_dumps,
+    json_bytes,
 )
 from homeassistant.helpers.service import async_get_all_descriptions
 from homeassistant.helpers.typing import EventType
@@ -460,7 +460,7 @@ def _send_handle_entities_init_response(
     )
 
 
-async def _async_get_all_descriptions_json(hass: HomeAssistant) -> str:
+async def _async_get_all_descriptions_json(hass: HomeAssistant) -> bytes:
     """Return JSON of descriptions (i.e. user documentation) for all service calls."""
     descriptions = await async_get_all_descriptions(hass)
     if ALL_SERVICE_DESCRIPTIONS_JSON_CACHE in hass.data:
@@ -469,8 +469,8 @@ async def _async_get_all_descriptions_json(hass: HomeAssistant) -> str:
         ]
         # If the descriptions are the same, return the cached JSON payload
         if cached_descriptions is descriptions:
-            return cast(str, cached_json_payload)
-    json_payload = json_dumps(descriptions)
+            return cast(bytes, cached_json_payload)
+    json_payload = json_bytes(descriptions)
     hass.data[ALL_SERVICE_DESCRIPTIONS_JSON_CACHE] = (descriptions, json_payload)
     return json_payload
 
@@ -482,7 +482,7 @@ async def handle_get_services(
 ) -> None:
     """Handle get services command."""
     payload = await _async_get_all_descriptions_json(hass)
-    connection.send_message(construct_result_message(msg["id"], payload.encode()))
+    connection.send_message(construct_result_message(msg["id"], payload))
 
 
 @callback