docs: Various cleanup of outdated comments and docstrings (#31754)

- Remove pylint warning suppression from SHAKE-128 hexdigest calls; these
  are no longer needed as of astroid 2.12.12. For background, see issue
  <https://github.com/PyCQA/pylint/issues/4039>. Also, correct a comment
  that referred to SHAKE-256 instead of SHAKE-128.
- Replace "released" with "beta" in several places where there was a copy
  & paste error in dark_lang. Add mention of `beta_lang` to a docstring
  where it was omitted.
- Remove comment regarding Mongo startup; the code it referred to has since
  been removed.
- Fix typos.

openedx/core/djangoapps/user_authn/views/login.py

@@ -141,7 +141,7 @@ def _get_user_by_email_or_username(request, api_version):
         user = _get_user_by_username(email_or_username)
 
     if not user:
-        digest = hashlib.shake_128(email_or_username.encode('utf-8')).hexdigest(16)  # pylint: disable=too-many-function-args
+        digest = hashlib.shake_128(email_or_username.encode('utf-8')).hexdigest(16)
         AUDIT_LOG.warning(f"Login failed - Unknown user email or username {digest}")
 
     return user

openedx/core/djangoapps/user_authn/views/tests/test_login.py

@@ -337,7 +337,6 @@ class LoginTest(SiteMixin, CacheIsolationTestCase, OpenEdxEventsTestMixin):
 
     def test_login_fail_no_user_exists(self):
         nonexistent_email = 'not_a_user@edx.org'
-        # pylint: disable=too-many-function-args
         email_hash = hashlib.shake_128(nonexistent_email.encode('utf-8')).hexdigest(16)
         response, mock_audit_log = self._login_response(
             nonexistent_email,
@@ -442,7 +441,6 @@ class LoginTest(SiteMixin, CacheIsolationTestCase, OpenEdxEventsTestMixin):
         the system does *not* send account activation email notification to the user.
         """
         nonexistent_email = 'incorrect@email.com'
-        # pylint: disable=too-many-function-args
         email_hash = hashlib.shake_128(nonexistent_email.encode('utf-8')).hexdigest(16)
         self.user.is_active = False
         self.user.save()
@@ -454,7 +452,6 @@ class LoginTest(SiteMixin, CacheIsolationTestCase, OpenEdxEventsTestMixin):
 
     def test_login_unicode_email(self):
         unicode_email = self.user_email + chr(40960)
-        # pylint: disable=too-many-function-args
         email_hash = hashlib.shake_128(unicode_email.encode('utf-8')).hexdigest(16)
         response, mock_audit_log = self._login_response(
             unicode_email,