Description

docker service ps for a service is supposed to group tasks together by slot, but global services don't have a slot. It looks here like the intention is that tasks running on the same node should get grouped together and historical tasks should get a \_ prefix so that they get indented under their other tasks on that same node:

https://github.com/docker/cli/blob/master/cli/command/task/print.go#L71

But this doesn't work because we sort tasks by slot:

https://github.com/docker/cli/blob/master/cli/command/task/print.go#L15

But global services' tasks don't have a slot.

Steps to reproduce the issue:

1. Create a global service on multiple nodes
2. Run docker service ps on that node
3. See that the service's tasks are not sorted by node