Problem description: If the user inserts a utf8mb4 smiley into the login field in user login form, then a failed SQL statement is returned in the error message, in case if Zabbix, that works with a MySQL database, is compiled without utf8mb4 support:

Steps to reproduce:

1. Setup zabbix with MySQL without utf8mb4 support
2. Open login page
3. Insert a smiley into the login field (for example 🔥 or 🌭)
4. Press "Sign in" button

Result: The failed query is displayed in the error message (see the above screenshot)
Expected: Same as in case of PostgreSQL, we shouldnot expose such information as table structure to users that are not even logged in. Expected error message:

Incorrect user name or password or account is temporarily blocked.