Consolidate MFE redirect logic

Its ripe for confusion to have this logic split between two separate
methods. This consolidation should make things easier to understand and
hopefully, less issue prone.

We don't really benefit from having two methods here anyway, as one is
_only_ ever called by the other.

It's also misleading that the second helper, in `toggles.py`, _also_
checks the FEATURE flag, as well as the waffle flag.

lms/djangoapps/courseware/toggles.py

@@ -37,11 +37,3 @@ REDIRECT_TO_COURSEWARE_MICROFRONTEND = ExperimentWaffleFlag(WAFFLE_FLAG_NAMESPAC
 # .. toggle_tickets: TNL-6982
 # .. toggle_status: supported
 COURSEWARE_MICROFRONTEND_COURSE_TEAM_PREVIEW = CourseWaffleFlag(WAFFLE_FLAG_NAMESPACE, 'microfrontend_course_team_preview')
-
-
-def should_redirect_to_courseware_microfrontend(course_key):
-    return (
-        settings.FEATURES.get('ENABLE_COURSEWARE_MICROFRONTEND') and
-        (not course_key.deprecated) and  # Old Mongo courses not supported
-        REDIRECT_TO_COURSEWARE_MICROFRONTEND.is_enabled(course_key)
-    )

lms/djangoapps/courseware/views/index.py

@@ -74,7 +74,6 @@ from ..permissions import MASQUERADE_AS_STUDENT
 from ..toggles import (
     COURSEWARE_MICROFRONTEND_COURSE_TEAM_PREVIEW,
     REDIRECT_TO_COURSEWARE_MICROFRONTEND,
-    should_redirect_to_courseware_microfrontend,
 )
 from ..url_helpers import get_microfrontend_url
 
@@ -186,16 +185,20 @@ class CoursewareIndex(View):
         Redirect to the new courseware micro frontend,
         unless this is a time limited exam.
         """
-        # learners should redirect, if the waffle flag is set
-        if should_redirect_to_courseware_microfrontend(self.course_key):
-            # but exams should not redirect to the mfe until they're supported
-            if getattr(self.section, 'is_time_limited', False):
-                return
-
-            # and staff will not redirect, either
-            if self.is_staff:
-                return
-
+        # DENY: feature disabled globally
+        if not settings.FEATURES.get('ENABLE_COURSEWARE_MICROFRONTEND'):
+            return
+        # DENY: staff access
+        if self.is_staff:
+            return
+        # DENY: Old Mongo courses, until removed from platform
+        if self.course_key.deprecated:
+            return
+        # DENY: Timed Exams, until supported
+        if getattr(self.section, 'is_time_limited', False):
+            return
+        # ALLOW: when flag set for course
+        if REDIRECT_TO_COURSEWARE_MICROFRONTEND.is_enabled(self.course_key):
             raise Redirect(self.microfrontend_url)
 
     @property