!1061 扩展逻辑复制时候，cmd命令的长度限制从1024到100*1024

Merge pull request !1061 from 刘伟/extend-walsender-cmd-len

src/gausskernel/storage/replication/walsender.cpp

@@ -1795,7 +1795,7 @@ bool cmdStringCheck(const char *cmd_string)
  *   */
 static bool cmdStringLengthCheck(const char* cmd_string)
 {
-    const size_t cmd_length_limit = 1024;
+    const size_t cmd_length_limit = 1024*100;
     const size_t slotname_limit = 64;
     char comd[cmd_length_limit] = {'\0'};
     char* sub_cmd = NULL;