Airflow 2.1.0, Docker

**What happened**:

Users with the Guest role assigned are stuck in a redirect loop once they attempt to login successfully to the web interface.

**What you expected to happen**:

Get minimal access to the dashboard with the appropriate views for a guest role

**How to reproduce it**:
1. Assign a guest role to any user and remove any other roles with the administrator user.
2. Logout from the admin account 
3. Login as the guest user
4. You will notice constant HTTP redirects, and the dashboard will not show up.


airflow/www/security.py
from sqlalchemy.orm import joinedload
from airflow.exceptions import AirflowException
from airflow.models import DagBag, DagModel
from airflow.security import permissions
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.session import provide_session
from airflow.www.utils import CustomSQLAInterface
from airflow.www.views import (
    CustomPermissionModelView,
    CustomPermissionViewModelView,
    CustomResetMyPasswordView,
    CustomResetPasswordView,
    CustomRoleModelView,
    CustomUserDBModelView,
    CustomUserInfoEditView,
    CustomUserLDAPModelView,
    CustomUserOAuthModelView,
    CustomUserOIDModelView,
    CustomUserRemoteUserModelView,
    CustomUserStatsChartView,
    CustomViewMenuModelView,
)
EXISTING_ROLES = {
    'Admin',
    'Viewer',
    'User',
    'Op',
    'Public',
}
class AirflowSecurityManager(SecurityManager, LoggingMixin):