Keep the salvaged coverage from #112457 at the repo's 1-2 invariant tests
per fix: one parametrized test over every spec-legal terminator pair cut at
every chunk seam (plus the three-way dribble and two completed events in a
single chunk, which the rfind-based cap lumped into one charge), and one
negative pinning that a CRLF straddling the seam is a line ending, not a
boundary. The non-straddled CRLF negative and the "split boundary before an
over-cap event" case are dropped: the straddled variant subsumes the former
and test_sse_event_over_cap_rejected already pins the latter's invariant.
3367adfa21