**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

tests/models/test_baseoperator.py
def __init_subclass__(cls, class_arg=None, **kwargs) -> None:
            cls._class_arg = class_arg
            super().__init_subclass__(**kwargs)
        def execute(self, context):
            self.context_arg = context
    class_arg = "foo"
    context = {"key": "value"}
    class ConcreteSubclassOp(InitSubclassOp, class_arg=class_arg):
        pass
    task = ConcreteSubclassOp(task_id="op1")
    task_copy = task.prepare_for_execution()
    task_copy.execute(context)
    assert task_copy._class_arg == class_arg
    assert task_copy.context_arg == context