Upgrade Grails version on both Grails-based applications to 3.3.3

Upgraded both Grails-based applications from 3.3.2 to 3.3.3. I generated blank Grails 3.3.2 and 3.3.3 apps and compared key files as necessary.

• build.gradle
• gradle.properties
• grails-app/assets/stylesheets/grails.css
• grails-app/assets/stylesheets/main.css
• grails-app/conf/application.yml
• grails-app/i18n/messages_cs.properties
• grails-app/i18n/messages_cs_CZ.properties
• grails-app/i18n/messages_sk.properties
• src/integration-test/resources/GebConfig.groovy