chore:add,update prints in leaf/branch_stage tests

[gabriele-0201]

printlns aims to simplify debugging in case of a bug found in the update logic A future pr will contain a refactor of those prints to be part of a dump if the test fails.

edit. it's not worth adding complexity to print things on CI if the test is easily reproducible locally

[gabriele-0201]

• chore:add,update prints in leaf/branch_stage tests #566 👈 (View in Graphite)
• refactor: follow-up to leaf updater uses binary search #565 : 1 other dependent PR (#570 )
• fix: update BaseLeaf when keep_up_to jumps to end #564
• master

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[rphmeier]

I don't like having printlns committed, even in tests. Often, the prints that are best to add are very dependent on the issue you're debugging. I would prefer to reject this change, even if it means adding the prints redundantly when debugging.

[rphmeier]

The exception being when the test is random, and we need to somehow save the seed. But that should be it!

[gabriele-0201]

No problem rejecting this. I also don't like printlns on the master branch.
However, since they were added in this commit, I simply wanted to make them symmetric between the leaf and branch stages, but this seems to be a total misunderstanding. I will modify #570 and remove the unnecessary printlns there