**Apache Airflow version**: 2.0.0b* / master


**What happened**:

`[ldap]` section in `airflow.cfg` is not applicable anymore in 2.0 and `master`, because the LDAP authentication (for webserver and API) is handled by FAB, and the configuration for this is handled by `webserver_config.py` file.

![airflow_–_default_airflow_cfg](https://user-images.githubusercontent.com/11539188/99289209-ef210700-283c-11eb-948e-16811ba09293.png)


**What you expected to happen**:

The `[ldap]` section should be removed from `airflow/config_templates/default_airflow.cfg` and `airflow/config_templates/config.yml` (and some other applicable files).

Otherwise leaving this section there will be a big confusion for users.
airflow/configuration.py
"""Get path to Airflow Home"""
    return expand_env_var(os.environ.get('AIRFLOW_HOME', '~/airflow'))
def get_airflow_config(airflow_home):
    """Get Path to airflow.cfg path"""
    if 'AIRFLOW_CONFIG' not in os.environ:
        return os.path.join(airflow_home, 'airflow.cfg')
    return expand_env_var(os.environ['AIRFLOW_CONFIG'])
AIRFLOW_HOME = get_airflow_home()
AIRFLOW_CONFIG = get_airflow_config(AIRFLOW_HOME)
pathlib.Path(AIRFLOW_HOME).mkdir(parents=True, exist_ok=True)
_TEST_DAGS_FOLDER = os.path.join(
    os.path.dirname(os.path.dirname(os.path.realpath(__file__))), 'tests', 'dags'
)
if os.path.exists(_TEST_DAGS_FOLDER):
    TEST_DAGS_FOLDER = _TEST_DAGS_FOLDER
else:
    TEST_DAGS_FOLDER = os.path.join(AIRFLOW_HOME, 'dags')
_TEST_PLUGINS_FOLDER = os.path.join(
    os.path.dirname(os.path.dirname(os.path.realpath(__file__))), 'tests', 'plugins'
)
if os.path.exists(_TEST_PLUGINS_FOLDER):
    TEST_PLUGINS_FOLDER = _TEST_PLUGINS_FOLDER
else:
    TEST_PLUGINS_FOLDER = os.path.join(AIRFLOW_HOME, 'plugins')
def parameterized_config(template):