SERVER-21157 Change term warning message in protocol version 0 to LOG(3)

Author: visualzhou

src/mongo/db/repl/replication_coordinator_impl.cpp

@@ -3128,7 +3128,7 @@ Status ReplicationCoordinatorImpl::updateTerm(long long term) {
 
 bool ReplicationCoordinatorImpl::_updateTerm_incallback(long long term) {
     if (!isV1ElectionProtocol()) {
-        warning() << "Cannot update term in election protocol version 0";
+        LOG(3) << "Cannot update term in election protocol version 0";
         return false;
     }