MDEV-18046: Assortment of crashes, assertion failures and ASAN errors in mysql_show_binlog_events

Problem:
========
SHOW BINLOG EVENTS FROM <pos> reports following assert when ASAN is enabled.

Query_log_event::Query_log_event(const char*, uint,
    const Format_description_log_event*, Log_event_type):
  Assertion `(pos) + (6) <= (end)' failed

Fix:
===
**Part9: Removed additional DBUG_ASSERT**

sql/log_event.cc

@@ -3502,7 +3502,6 @@ code_name(int code)
 #define CHECK_SPACE(PTR,END,CNT)                      \
   do {                                                \
     DBUG_PRINT("info", ("Read %s", code_name(pos[-1]))); \
-    DBUG_ASSERT((PTR) + (CNT) <= (END));              \
     if ((PTR) + (CNT) > (END)) {                      \
       DBUG_PRINT("info", ("query= 0"));               \
       query= 0;                                       \