JDK 17 required for Cassandra 5.0

Cassandra 5.0 requires JDK 17, dropping support for JDK 8 and 11. This is a breaking change requiring JVM upgrade before Cassandra upgrade.

Upgrade to JDK 17 before attempting Cassandra 5.0 upgrade. Review JVM flags for JDK 17 compatibility and remove deprecated options. Test application drivers for JDK 17 compatibility. Monitor JVM metrics post-upgrade for GC behavior changes and performance regression.