**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
"""Returns True if the Operator has been assigned to a DAG."""
        return getattr(self, '_dag', None) is not None
    @property
    def dag_id(self) -> str:
        """Returns dag id if it has one or an adhoc + owner"""
        if self.has_dag():
            return self.dag.dag_id
        else:
            return 'adhoc_' + self.owner
    deps: Iterable[BaseTIDep] = frozenset(
        {
            NotInRetryPeriodDep(),
            PrevDagrunDep(),
            TriggerRuleDep(),
            NotPreviouslySkippedDep(),
        }
    )
    """
    Returns the set of dependencies for the operator. These differ from execution
    context dependencies in that they are specific to tasks and can be
    extended/overridden by subclasses.
    """
    def prepare_for_execution(self) -> "BaseOperator":