feat!: Remove the course sock and related APIs.

DEPR: https://github.com/openedx/edx-platform/issues/36429

This change removes the course_sock and related API data.  The UI it
removes is on the Legacy Courseware pages which have also been replaced
and have their own [deprecation ticket](https://github.com/openedx/edx-platform/issues/35803)

Before this can be merged, we will need to update the
frontend-app-learning MFE to no longer consume the
`can_show_upgrade_sock` attribute.

BREAKING CHANGE: CourseHomeMetadata, ProgressTab, OutlineTab and
VerifiedMode APIs will no longer have a `can_show_upgrade_sock`
attribute.

openedx/core/djangoapps/courseware_api/serializers.py

@@ -80,7 +80,6 @@ class CourseInfoSerializer(serializers.Serializer):  # pylint: disable=abstract-
     """
 
     access_expiration = serializers.DictField()
-    can_show_upgrade_sock = serializers.BooleanField()
     content_type_gating_enabled = serializers.BooleanField()
     course_goals = CourseGoalsSerializer()
     effort = serializers.CharField()

openedx/core/djangoapps/courseware_api/views.py

@@ -55,7 +55,6 @@ from openedx.core.djangoapps.programs.utils import ProgramProgressMeter
 from openedx.core.lib.api.authentication import BearerAuthenticationAllowInactiveUser
 from openedx.core.lib.api.view_utils import DeveloperErrorViewMixin
 from openedx.core.lib.courses import get_course_by_id
-from openedx.features.course_experience import DISPLAY_COURSE_SOCK_FLAG
 from openedx.features.course_experience import ENABLE_COURSE_GOALS
 from openedx.features.content_type_gating.models import ContentTypeGatingConfig
 from openedx.features.course_duration_limits.access import get_access_expiration_data
@@ -127,10 +126,6 @@ class CoursewareMeta:
             course_key=self.course_key,
         )
 
-    @property
-    def can_show_upgrade_sock(self):
-        return DISPLAY_COURSE_SOCK_FLAG.is_enabled(self.course_key)
-
     @property
     def license(self):
         return self.course.license