The log level of Hibernate Validator is (obviously) not DEBUG by default so you must have something in your application classpath setting the log level to DEBUG.
Hibernate Validator is using JBoss Logging which uses log4j under the hood so log4j.logger.org.hibernate.validator=info
in your log4j.properties should work.
But considering it shouldn't have been set to DEBUG in the first place, I'm wondering if you have something in your classpath overriding your log configuration.
I suspect either you or a dependency have enabled DEBUG logging for org.hibernate to see the queries or something similar and this is this setting you should find and remove.