mlog: do not display http errors by default

They're controllable by potential attackers and would just spam

contrib/epee/src/mlog.cpp

@@ -97,7 +97,7 @@ static const char *get_default_categories(int level)
   switch (level)
   {
     case 0:
-      categories = "*:WARNING,net:FATAL,net.p2p:FATAL,net.cn:FATAL,global:INFO,verify:FATAL,stacktrace:INFO,logging:INFO,msgwriter:INFO";
+      categories = "*:WARNING,net:FATAL,net.http:FATAL,net.p2p:FATAL,net.cn:FATAL,global:INFO,verify:FATAL,stacktrace:INFO,logging:INFO,msgwriter:INFO";
       break;
     case 1:
       categories = "*:INFO,global:INFO,stacktrace:INFO,logging:INFO,msgwriter:INFO";