**Description**

It would be nice if the weight_rule default value could be managed by a global config

suggested config:
```
# Weighting method used for the effective total priority weight of the task. 
# Options are: { downstream | upstream | absolute } default is
default_weight_rule = downstream
```
**Use case / motivation**

In some pipeline, you really need to have absolute weight, and then you have to add a line in each task definition which is annoying

airflow/configuration.py
"""Historical as_dict"""
    warnings.warn(
        "Accessing configuration method 'as_dict' directly from the configuration module is "
        "deprecated. Please access the configuration from the 'configuration.conf' object via "
        "'conf.as_dict'",
        DeprecationWarning,
        stacklevel=2,
    )
    return conf.as_dict(*args, **kwargs)
def set(*args, **kwargs):
    """Historical set"""
    warnings.warn(
        "Accessing configuration method 'set' directly from the configuration module is "
        "deprecated. Please access the configuration from the 'configuration.conf' object via "
        "'conf.set'",
        DeprecationWarning,
        stacklevel=2,
    )
    return conf.set(*args, **kwargs)
def ensure_secrets_loaded() -> List[BaseSecretsBackend]:
    """
    Ensure that all secrets backends are loaded.
    If the secrets_backend_list contains only 2 default backends, reload it.
    """
    
    if len(secrets_backend_list) == 2:
        return initialize_secrets_backends()
    return secrets_backend_list
def get_custom_secret_backend() -> Optional[BaseSecretsBackend]: