Backend failed handshake is now a detected

Backend failed handshake is now a detected and MYSQL_HANDSHAKE_FAILED s
set.

Reload users from backend is now restricted to MYSQL_AUTH_FAILED only

server/modules/include/mysql_client_server_protocol.h

@@ -95,6 +95,7 @@ typedef enum {
         MYSQL_AUTH_SENT,
         MYSQL_AUTH_RECV,
         MYSQL_AUTH_FAILED,
+        MYSQL_HANDSHAKE_FAILED,
         MYSQL_IDLE
 } mysql_auth_state_t;