Apply warm shutdown across coordinators

### Body Python coordinator implements this in #69034. We should make this also available for other coordinators. A small-scale refactoring to move the context manager to ActivityProcess so we can do something like: ```python class ActivitySubprocess: @classmethod def run(cls, **kwargs): with _warm_shutdown_signals(): self = cls.start(**kwargs) exit_code = self.wait() return exit_code, self ``` and just use this instead of calling things separately. All coordinators can switch to use this new function. Language side shoould be fine as-is; dedicated signal handling improvements can be made but they are not specific to this. ### Committer - [x] I acknowledge that I am a maintainer/committer of the Apache Airflow project.