Revert "Make test assertions compatible with fix in 715f62fe for #114"

This reverts commit e5745844e7781329a18f746326202aa7590c2a30.
Revert "apply both query:start and query:end on occurrence:start, not occurrence:end, refs #114"

This reverts commit 715f62fe29676ec20d7a1013f16f1c7abdd8dae8.
Setting 23:59 end times is a feature, not a bug. Close #116.

But maybe you do want to exclude ongoing events. In that case:
- either override the data_postprocessing event handler
- or use the #120 API extension with a start_min filter
extract optimization tests into separate testcase refs #114
refactor performance tests refs #114
refactor start sorting to prepare end sorting
generalize performance filter/resort to also cover end sorting, refs #114