Honor sybase as database value, and remove the unused field databaseDialects in DatabaseTimerPersistence class

org.jboss.as.ejb3.timerservice.persistence.database.DatabaseTimerPersistence#databaseDialects is only used in informational logging, and this info can be kept somewhere else, e.g., in attribute description.

The method to get this value: org.jboss.as.ejb3.timerservice.persistence.database.DatabaseTimerPersistence#extractDialects can also be removed.

This method looks in all keys in sql properties for any keys specific for any database product, and this can be an inaccurate list of supported database products.

Another problem with dialect processing, if one configures database-data-store with attribute = sybase, this value is reset to null during dialect normalization. This should be fixed to honor user's valid configuration.