Laurence Watts

Fix sending event messages to non-subscribers

4

Closes https://github.com/dask/distributed/issues/7013 - [x] Tests added / passed - [x] Passes `pre-commit run --all-files`

**What happened**: Events sent by `log_event` are sent to all registered clients, whether or not they have subscribed to the topic. When more than one client is subscribed to the...

**Describe the issue**: When using unique keys for each task, tasks appear to be distributed completely to workers immediately regardless of worker saturation config (i.e. matching the behaviour if `distributed.scheduler.worker-saturation`...