fix: update discussions MFE path [BD-38] [TNL-9347] (#29691)

* fix: update discussiosn MFE path

* squash!: fix tests

lms/djangoapps/courseware/tests/test_discussion_xblock.py

@@ -330,7 +330,7 @@ class TestXBlockInCourse(SharedModuleStoreTestCase):
             <iframe
                 id='discussions-mfe-tab-embed'
                 title='Discussions'
-                src='http://test.url/discussions/edX/toy/2012_Fall/topics/test_discussion_xblock_id'
+                src='http://test.url/edX/toy/2012_Fall/topics/test_discussion_xblock_id'
             />
             """,
             html,

lms/djangoapps/discussion/django_comment_client/tests/test_utils.py

@@ -1236,7 +1236,7 @@ class DiscussionTabTestCase(ModuleStoreTestCase):
 
     @override_settings(DISCUSSIONS_MICROFRONTEND_URL="http://test.url")
     @ddt.data(
-        (True, 'http://test.url/discussions/{}/'),
+        (True, 'http://test.url/{}/'),
         (False, '/courses/{}/discussion/forum/'),
     )
     @ddt.unpack