Remove warning about compound tags deprecation

[oliverholworthy]

Remove warning about compound tags deprecation. Since the warning message here is not currently easily actionable by users. And prints a message every time a ColumnSchema is created, resulting in distracting messages in logs.

After discussions about this we are considering keeping the compound tags for backwards compatibility for now.

If we reach a point where we're using the narrower tags only across Merlin, we can revisit the deprecation approach for these

[karlhigley]

Wait, I thought the result of the discussion involved providing a way to select by all tags and using that instead of the compound tags? I'm in favor of the warning going away, but I didn't want to remove it until we actually addressed the underlying issue.

[oliverholworthy]

Providing a way to simplify selecting by all tags was one of the outcomes. However we also discussed two other things. Keeping the compound tags around as a convenient shortcut and removing the warning.

The current state of things seems to be that the warning is not actionable. Which suggests that it would likely be clearer to users of our packages if it wasn't printed/logged.

[karlhigley]

The current state of things seems to be that the warning is not actionable.

I think it is actionable now that select_by_tag allows you to choose between union/intersection modes, but 🤷🏻

[github-actions]

Documentation preview

https://nvidia-merlin.github.io/core/review/pr-256