**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/models/baseoperator.py
def __init__(self):
                self.warnings = __import__('warnings')
            def __getattr__(self, name):
                return getattr(self.warnings, name)
            def __dir__(self):
                return dir(self.warnings)
            def warn(self, message, category=None, stacklevel=1, source=None):
                self.warnings.warn(message, category, stacklevel + 2, source)
        if func.__globals__.get('warnings') is sys.modules['warnings']:
            
            
            
            
            func.__globals__['warnings'] = autostacklevel_warn()
        @functools.wraps(func)
        def apply_defaults(self, *args: Any, **kwargs: Any) -> Any:
            from airflow.models.dag import DagContext
            from airflow.utils.task_group import TaskGroupContext
            if len(args) > 0:
                raise AirflowException("Use keyword arguments when initializing operators")
            dag_args: Dict[str, Any] = {}
            dag_params: Dict[str, Any] = {}
            dag = kwargs.get('dag') or DagContext.get_current_dag()
            if dag:
                dag_args = copy.copy(dag.default_args) or {}
                dag_params = copy.deepcopy(dag.params) or {}
                task_group = TaskGroupContext.get_current_task_group(dag)
                if task_group:
                    dag_args.update(task_group.default_args)
            params = kwargs.get('params', {}) or {}