Add an option to hide MULTI_NODE_INSTANCE Tasks

[tensorpro]

Proposal Summary

Add a filtering option that can hide MULTI_NODE_INSTANCE tasks.

Motivation

When running a multi node task that runs on several nodes, the dashboard gets filled up with several "MULTI_NODE_INSTANCE" tasks for the same training run. It would be nice to have a way to see just the parent tasks.

[ainoam]

Thanks for suggesting @tensorpro. We'll consider how to best accommodate in future versions.