**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
from airflow.lineage import apply_lineage, prepare_lineage
from airflow.models.base import Operator
from airflow.models.param import ParamsDict
from airflow.models.pool import Pool
from airflow.models.taskinstance import Context, TaskInstance, clear_task_instances
from airflow.models.taskmixin import TaskMixin
from airflow.models.xcom import XCOM_RETURN_KEY
from airflow.ti_deps.deps.base_ti_dep import BaseTIDep
from airflow.ti_deps.deps.not_in_retry_period_dep import NotInRetryPeriodDep
from airflow.ti_deps.deps.not_previously_skipped_dep import NotPreviouslySkippedDep
from airflow.ti_deps.deps.prev_dagrun_dep import PrevDagrunDep
from airflow.ti_deps.deps.trigger_rule_dep import TriggerRuleDep
from airflow.triggers.base import BaseTrigger
from airflow.utils import timezone
from airflow.utils.edgemodifier import EdgeModifier
from airflow.utils.helpers import validate_key
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.operator_resources import Resources
from airflow.utils.session import provide_session
from airflow.utils.trigger_rule import TriggerRule
from airflow.utils.weight_rule import WeightRule
if TYPE_CHECKING:
    from airflow.models.xcom_arg import XComArg
    from airflow.utils.task_group import TaskGroup
ScheduleInterval = Union[str, timedelta, relativedelta]
TaskStateChangeCallback = Callable[[Context], None]
TaskPreExecuteHook = Callable[[Context], None]
TaskPostExecuteHook = Callable[[Context, Any], None]
T = TypeVar('T', bound=Callable)
class BaseOperatorMeta(abc.ABCMeta):