feat: in-context discussion for units can be disabled by default (#35414)

This PR, adds to the ability to keep the in-context discussions disabled by default. That way all new units which are added will have the discussions sidebar disabled and can be individually enabled by the course instructors.

cms/envs/common.py

@@ -566,6 +566,14 @@ FEATURES = {
     # .. toggle_use_cases: open_edx
     # .. toggle_creation_date: 2024-04-10
     'BADGES_ENABLED': False,
+
+    # .. toggle_name: FEATURES['IN_CONTEXT_DISCUSSION_ENABLED_DEFAULT']
+    # .. toggle_implementation: DjangoSetting
+    # .. toggle_default: True
+    # .. toggle_description: Set to False to disable in-context discussion for units by default.
+    # .. toggle_use_cases: open_edx
+    # .. toggle_creation_date: 2024-09-02
+    'IN_CONTEXT_DISCUSSION_ENABLED_DEFAULT': True,
 }
 
 # .. toggle_name: ENABLE_COPPA_COMPLIANCE

xmodule/vertical_block.py

@@ -9,6 +9,7 @@ from datetime import datetime
 from functools import reduce
 
 import pytz
+from django.conf import settings
 from lxml import etree
 from openedx_filters.learning.filters import VerticalBlockChildRenderStarted, VerticalBlockRenderCompleted
 from web_fragments.fragment import Fragment
@@ -43,7 +44,7 @@ class VerticalFields:
     discussion_enabled = Boolean(
         display_name=_("Enable in-context discussions for the Unit"),
         help=_("Add discussion for the Unit."),
-        default=True,
+        default=settings.FEATURES.get('IN_CONTEXT_DISCUSSION_ENABLED_DEFAULT', True),
         scope=Scope.settings,
     )