pseudo_thread_id Can Overflow on Binlog Write

Though the thread_id type is 8 bytes long, it can't actually have a value larger than 4 bytes (MDEV-15089). However, the global variable pseudo_thread_id is 8 bytes long, can be set dynamically, and when so, only the first 4 bytes are written to the thread_id field of a binary log's Query_log_event and Gtid_log_event (Gtid_log_event debuting in 11.5 with MDEV-7850). So if a user sets the pseudo_thread_id to be larger than 4 bytes, it is truncated. The value should be restricted to be within the 4-byte range.