WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
Talend StudioのFile menu -> "Edit Project properties" -> expand "Job Settings" -> click "Stats & Logs" -> from right-side pane you see where you have specified your Mysql DB details -> in the "Additional parameters" field set it to "useSSL=false" -> Ok to save/apply.