Revert !743 catching of edge-case missed hits in dataprocessor, and add edge cases to Itkpixv2/Rd53b tests

After a couple months of debugging the strange dataprocessor state induced by early return for HMAP retrieval (see here) @okovanda, @mamirono and I have decided that it would be better to revert to the state where we are dropping some hits until we have the time to figure out a stable way to prevent this. This will fix issue #269 and related, while inducing a new issue #278.

This will also add edge case tests that caused segfaults in !743 (merged).