Reduce MAX_HEADERS_RESULTS
Reduce MAX_HEADERS_RESULTS

because 2000 Headers occupy more than 32 megabytes (maximum message size) and cause disconnection of nodes
Kcoin-project/kcoin,Kcoin-project/kcoin,Kcoin-project/kcoin,Kcoin-project/kcoin,Kcoin-project/kcoin,Kcoin-project/kcoin