Add a BiE-specific warning when semi-sync master times out on a replica that never sent a GTID ack

Setup:

• Master: 13.2.0-debug (MDEV-38190 branch) with --binlog-storage-engine=innodb --log-bin, rpl_semi_sync_master_enabled=1, rpl_semi_sync_master_timeout=5000.
• Slave: 12.3.1 GA with rpl_semi_sync_slave_enabled=1, MASTER_USE_GTID=slave_pos, MASTER_SSL=0.
• Start both servers and run START SLAVE. On the master, create test.t1 and run 3 single-row INSERTs.

A BiE master waits for semi-sync acks that identify the transaction by GTID. A slave without GTID-ack support completes the handshake, so the master shows Rpl_semi_sync_master_clients=1 and Rpl_semi_sync_master_status=ON. It never sends an ack the master can match. The first commit waits the full timeout (5.07 s), and the master logs only:

[Warning] Timeout waiting for reply of binlog (file: binlog-000000.ibb, pos:16646), last semi-sync at file (none), position 0 GTID 0-0-0.
[Note] Semi-sync replication switched OFF.

The message is the same one a slow network or a dead slave produces. Nothing says the cause is a format mismatch between a BiE master and an older replica. Semi-sync then silently falls back to async. The behavior is correct and all rows replicate. Only the diagnostics are missing, and only under BiE with semi-sync.