The fix for SPR-17178 switched from debug to warn level warning for
all sub-classes of AbstractHandlerExceptionResolver where the request
concerned the DefaultHandlerExceptionResolver only.
This commit restores the original DEBUG level logging that was in
AbstractHandlerExceptionResolver from before SPR-17178. In addition
DefaultHandlerExceptionResolver registers a warnLogCategory by default
which enables warn logging and hence fulfilling the original goal
for SPR-17178.
Issue: SPR-17383