Spring Do not count exchanges outcomes as UNKNOWN if response was committed

Per this comment, we should not mark observed HTTP server exchanges as "UNKNOWN" outcomes if the response was committed. Chances are very high that the response was sent but that the client closed the connection aggressively before we had a chance to complete the exchange properly.

We should instead only count UNKNOWN outcomes if the client disconnected and the response was not committed.

Comment From: bclozel

Superseded by #31417 - we don't need this type of refinement when the root cause is probably going to be addressed directly in the instrumentation.