List full dashboard address in scheduler logs

[jrbourbeau]

When users run dask scheduler, logs like the following are emitted

2023-02-14 10:17:38,016 - distributed.scheduler - INFO - -----------------------------------------------
2023-02-14 10:17:39,076 - distributed.scheduler - INFO - State start
2023-02-14 10:17:39,080 - distributed.scheduler - INFO - -----------------------------------------------
2023-02-14 10:17:39,082 - distributed.scheduler - INFO -   Scheduler at:  tcp://<ip-address>:8786
2023-02-14 10:17:39,082 - distributed.scheduler - INFO -   dashboard at:                     :8787

It'd be nice if instead of dashboard at: :8787, we listed the full dashboard address. That makes it a bit easier for users to navigate to the dashboard.