[dashboard] Don't start dashboard agent when missing dependencies (ra…

…y-project#17966)

LINT changes.

fall back to manual pin version

fall back to manual pin version

change to ray version 1.5.0

Rerun due to py36 wheel build failure

fix serve start namespace issue and add test (ray-project#16291)

Move scalability envelope back down to 250 nodes (ray-project#15381)

* .

* done?

* .

Co-authored-by: Alex Wu <alex@anyscale.com>

lint/docs

Remove suppress output to see why wheel is not building