[Server] Record only the dispatched command family; drop unused totals

processCommandContainer recorded every family in a container even though
the base if/else-if dispatch processes at most one. An unauthenticated
client could batch a session command (login) with fabricated developer,
moderator, and admin entries and forge genuine-looking samples that were
never executed or authorized. Mirror the base's selection, skip when the
handler was already deleted, and skip entries whose extension number is
-1 (which would otherwise wrap into the previous kind's id range).

[Server] Drop dead process-lifetime byte/uptime counters

txBytesTotal/rxBytesTotal added an atomic RMW to every socket write and
read for counters nothing consumes (cmdGetServerStats fills tx_bytes,
rx_bytes, and uptime_secs from the DB snapshot). Remove the two atomics
and the getTxBytesTotal/getRxBytesTotal/getUptimeSeconds getters; the
incTxBytes/incRxBytes slots and mutexes remain for the ISL legacy
counters.

[Protocol] Document kind 5 as developer in CommandStats

NumKinds is 6 and the server emits kind_index = 5 for developer
commands; the comment stopped at 4.

libcockatrice_protocol/libcockatrice/protocol/pb/response_get_server_stats.proto

@@ -2,7 +2,7 @@ syntax = "proto2";
 import "response.proto";
 
 message CommandStats {
-    optional uint32 kind_index = 1;       // 0=session, 1=room, 2=game, 3=moderator, 4=admin
+    optional uint32 kind_index = 1;       // 0=session, 1=room, 2=game, 3=moderator, 4=admin, 5=developer
     optional uint32 extension_number = 2; // protobuf extension number within the kind
     optional string command_name = 3;     // e.g. "session/Command_Ping"
     optional uint64 count = 4;            // number of times observed