MXS-1341: Ignore binlog checksums in avrorouter

If the binlog has binlog checksums enabled, the extra checksum bytes are
removed from the end of the event. The avrorouter assumes that whatever
caused the binlogs to appear in the first place already checked that the
checksums are OK.

Also removed one extra byte being added to the length of all query events.

server/modules/routing/avrorouter/avrorouter.h

@@ -276,6 +276,7 @@ typedef struct avro_instance
     pcre2_code              *alter_table_re;
     uint8_t event_types;
     uint8_t event_type_hdr_lens[MAX_EVENT_TYPE_END];
+    uint8_t binlog_checksum;
     gtid_pos_t              gtid;
     TABLE_MAP     *active_maps[MAX_MAPPED_TABLES];
     HASHTABLE     *table_maps;