**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
template_fields=["nested1"],
                ),
                {"foo": "bar"},
                ClassWithCustomAttributes(
                    nested1=ClassWithCustomAttributes(
                        att1="bar_1", att2="{{ foo }}_2", template_fields=["att1"]
                    ),
                    nested2=ClassWithCustomAttributes(
                        att3="{{ foo }}_3", att4="{{ foo }}_4", template_fields=["att3"]
                    ),
                    template_fields=["nested1"],
                ),
            ),
            (
                
                ClassWithCustomAttributes(att1=None, template_fields=["att1"]),
                {},
                ClassWithCustomAttributes(att1=None, template_fields=["att1"]),
            ),
            (
                
                object1,
                {"foo": "bar"},
                object1,
            ),
            
            ("{{ foo }}\n\n", {"foo": "bar"}, "bar\n"),
        ],
    )
    def test_render_template(self, content, context, expected_output):