AA-197: Provide cert upgrade info to learning MFE

Specifically, pass the MFE the audit access expiration date and
let it know when the upgrade deadline has passed, by not passing
any verified mode information along.

openedx/features/course_duration_limits/access.py

@@ -62,6 +62,8 @@ def get_user_course_duration(user, course):
       - Course access duration is bounded by the min and max duration.
       - If course fields are missing, default course access duration to MIN_DURATION.
     """
+    if not CourseDurationLimitConfig.enabled_for_enrollment(user, course):
+        return None
 
     enrollment = CourseEnrollment.get_enrollment(user, course.id)
     if enrollment is None or enrollment.mode != CourseMode.AUDIT:
@@ -107,9 +109,6 @@ def check_course_expired(user, course):
     if get_course_masquerade(user, course.id):
         return ACCESS_GRANTED
 
-    if not CourseDurationLimitConfig.enabled_for_enrollment(user, course):
-        return ACCESS_GRANTED
-
     expiration_date = get_user_course_expiration_date(user, course)
     if expiration_date and timezone.now() > expiration_date:
         return AuditExpiredError(user, course, expiration_date)
@@ -127,9 +126,6 @@ def generate_course_expired_message(user, course):
     """
     Generate the message for the user course expiration date if it exists.
     """
-    if not CourseDurationLimitConfig.enabled_for_enrollment(user, course):
-        return
-
     expiration_date = get_user_course_expiration_date(user, course)
     if not expiration_date:
         return