🎨(backend) use pylint error names instead of codes in disable comments

Replace pylint error codes with descriptive error names in disable comments
to make suppressed warnings explicit and improve code readability.

src/backend/core/services/livekit_events.py

@@ -1,6 +1,6 @@
 """LiveKit Events Service"""
 
-# pylint: disable=E1101
+# pylint: disable=no-member
 
 import uuid
 from enum import Enum

src/backend/core/services/participants_management.py

@@ -1,6 +1,6 @@
 """Participants management service for LiveKit rooms."""
 
-# pylint: disable=R0913,E0611,R0917
+# pylint: disable=too-many-arguments,no-name-in-module,too-many-positional-arguments
 # ruff: noqa:PLR0913
 
 import json