**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
self, content: Any, context: Dict, jinja_env: jinja2.Environment, seen_oids: Set
    ) -> None:
        if id(content) not in seen_oids:
            seen_oids.add(id(content))
            try:
                nested_template_fields = content.template_fields
            except AttributeError:
                
                return
            self._do_render_template_fields(content, nested_template_fields, context, jinja_env, seen_oids)
    def get_template_env(self) -> jinja2.Environment:
        """Fetch a Jinja template environment from the DAG or instantiate empty environment if no DAG."""
        return (
            self.dag.get_template_env()
            if self.has_dag()
            else airflow.templates.SandboxedEnvironment(cache_size=0)
        )
    def prepare_template(self) -> None: