Switch logic for using all-data in particle IO

[matthewturk]

After examining #2383, I came to believe that this logic was inverted.
In short, I believe that if is_all_data is True, we should be using
all of the data without validating. If it is False, we should check
for collisions.

[ngoldbaum]

Oops, my fault. Thanks for the fix!

It looks like this pointing at master instead of yt-4.0.

[matthewturk]

Whoops, you're right! I just changed the base and I think it's correctly pointed now.

[ngoldbaum]

This looks correct to me, thanks for fixing my bug!

It looks like github didn't re-trigger the tests when you changed the base, might need to either force-push a no-op amend commit or close and re-open the PR to get them to run on the correct branch.

[matthewturk]

@yt-fido please test this

[ngoldbaum]

I don’t think those can be cleared without udjusting the jenkins webhook since jenkins isn’t configured to run on this branch. Regardless this should be good to merge.

[brittonsmith]

@matthewturk assures me this is ok to merge, so I'm doing it.