Resolve Node.js deprecation warning, Gradle 8.5

[Kichura]

1. Updates checkout, setup-java, cache and upload-artifact to resolve the deprecation warning when viewing actions overview,
2. Removes the chmod +x gradlew statement as we do not need this,
3. Superseds the gradle/gradle-build-action step with gradle/actions/setup-gradle as the Gradle team advised this,
4. Updates Gradle to 8.5 along with the gradlew scripts.