Importing distributed.utils during ipython startup breaks jupyter

To reproduce the issue add the following to your ipython startup sequence (usually in /~/.ipython/profile_default/startup/00-imports.py)

```import distributed.utils```

The culprit is the following line:
https://github.com/dask/distributed/blob/8d300008e1c93525309198cc2e09405f6e2a8c04/distributed/utils.py#L1206

During startup jupyter_event_loop initialized is false and line 1206 is run. Importing distributed.utils after startup works fine, but if done during startup the ui is never able to connect to the kernel