From the logs in the internal repo, the experimental warning was being emitted
on the `__init__` function which is a bit confusing. We lift this message
up to the class level.
Previously, the warning emitted:
```
/dagster/dagster/core/run_coordinator/queued_run_coordinator.py:75: ExperimentalWarning: "__init__" is an experimental function. It may break in future versions, even between dot releases. To mute warnings for experimental functionality, set PYTHONWARNINGS=ignore::ExperimentalWarning in your environment or use one of the other methods described at https://docs.python.org/3/library/warnings.html#describing-warning-filters.
```