Respect dashboard prefix when redirecting root (#3387)
Respect dashboard prefix when redirecting root (#3387)

When --dashboard-prefix is used root location is always redirected to
/status without adding the prefix.

Fixes https://github.com/dask/distributed/issues/3405

Signed-off-by: Chrysostomos Nanakos <711c73f64afdce07b7e38039a96d2224209e9a6c@include.gr>
dask/distributed,blaze/distributed,dask/distributed,dask/distributed,blaze/distributed,dask/distributed