test: switch default test store to the split store

It's long past time that the default test modulestore was Split,
instead of Old Mongo. This commit switches the default store and
fixes some tests that now fail:
- Tests that didn't expect MFE to be enabled (because we don't
  enable MFE for Old Mongo) - opt out of MFE for those
- Tests that hardcoded old key string formats
- Lots of other random little differences

In many places, I didn't spend much time trying to figure out how to
properly fix the test, and instead just set the modulestore to Old
Mongo.

For those tests that I didn't spend time investigating, I've set
the modulestore to TEST_DATA_MONGO_AMNESTY_MODULESTORE - search for
that string to find further work.

common/djangoapps/student/tests/test_views.py

@@ -5,7 +5,6 @@ Test the student dashboard view.
 
 import itertools
 import json
-import re
 import unittest
 from datetime import datetime, timedelta  # lint-amnesty, pylint: disable=unused-import
 from unittest.mock import patch
@@ -642,16 +641,13 @@ class StudentDashboardTests(SharedModuleStoreTestCase, MilestonesTestCaseMixin,
         return ''.join(response.content.decode('utf-8').split())
 
     @staticmethod
-    def _pull_course_run_from_course_key(course_key_string):  # lint-amnesty, pylint: disable=missing-function-docstring
-        search_results = re.search(r'Run_[0-9]+$', course_key_string)
-        assert search_results
-        course_run_string = search_results.group(0).replace('_', ' ')
-        return course_run_string
+    def _pull_course_run_from_course_key(course_key: CourseKey):  # lint-amnesty, pylint: disable=missing-function-docstring
+        return course_key.run.replace('_', ' ')
 
     @staticmethod
     def _get_html_for_view_course_button(course_key_string, course_run_string):
         return '''
-            <a href="/courses/{course_key}/course/"
+            <a href="http://learning-mfe/course/{course_key}/home"
                class="course-target-link enter-course"
                data-course-key="{course_key}">
               View Course
@@ -679,7 +675,7 @@ class StudentDashboardTests(SharedModuleStoreTestCase, MilestonesTestCaseMixin,
         )
 
     @staticmethod
-    def _get_html_for_entitlement_button(course_key_string):
+    def _get_html_for_entitlement_button(course_key: CourseKey):
         return'''
             <div class="course-info">
             <span class="info-university">{org} - </span>
@@ -689,8 +685,8 @@ class StudentDashboardTests(SharedModuleStoreTestCase, MilestonesTestCaseMixin,
             </span>
             </div>
         '''.format(
-            org=course_key_string.split('/')[0],
-            course=course_key_string.split('/')[1]
+            org=course_key.org,
+            course=course_key.course,
         )
 
     def test_view_course_appears_on_dashboard(self):
@@ -711,7 +707,7 @@ class StudentDashboardTests(SharedModuleStoreTestCase, MilestonesTestCaseMixin,
         course_key_string = str(course.id)
         # No completion data means there's no block from which to resume.
         resume_block_key_string = ''
-        course_run_string = self._pull_course_run_from_course_key(course_key_string)
+        course_run_string = self._pull_course_run_from_course_key(course.id)
 
         view_button_html = self._get_html_for_view_course_button(
             course_key_string,
@@ -759,7 +755,7 @@ class StudentDashboardTests(SharedModuleStoreTestCase, MilestonesTestCaseMixin,
 
         course_key_string = str(course_key)
         resume_block_key_string = str(block_keys[-1])
-        course_run_string = self._pull_course_run_from_course_key(course_key_string)
+        course_run_string = self._pull_course_run_from_course_key(course_key)
 
         view_button_html = self._get_html_for_view_course_button(
             course_key_string,
@@ -840,8 +836,7 @@ class StudentDashboardTests(SharedModuleStoreTestCase, MilestonesTestCaseMixin,
 
             else:
                 last_completed_block_string = ''
-                course_run_string = self._pull_course_run_from_course_key(
-                    course_key_string)
+                course_run_string = self._pull_course_run_from_course_key(course_key)
 
             # Submit completed course blocks in even-numbered courses.
             if isEven(i):
@@ -871,9 +866,7 @@ class StudentDashboardTests(SharedModuleStoreTestCase, MilestonesTestCaseMixin,
                 )
             )
             html_for_entitlement.append(
-                self._get_html_for_entitlement_button(
-                    course_key_string
-                )
+                self._get_html_for_entitlement_button(course_key)
             )
 
         response = self.client.get(reverse('dashboard'))