ScyllaDB release: version 1.5

ScyllaDB 1.5 is a minor release of the open-source NoSQL database, ScyllaDB, which is compatible with Apache Cassandra and known for its high performance and low latency. This release emphasizes stability, bug fixes, and workload conditioning, a feature that allows ScyllaDB to self-tune to better handle various user workloads by automatically adjusting the rate of incoming requests based on disk performance. Key new features include the introduction of the "scylla-blocktune" script for optimizing data file and commitlog directories, and the disabling of Linux I/O scheduler settings to improve latency. The update also addresses notable bugs, such as unnecessary parallel queries in range scans, memory leaks during concurrent reads and writes, and startup issues on machines with many cores. Additionally, new metrics have been introduced to monitor performance under workload conditioning, specifically focusing on operations delayed due to disk speed limitations. The release encourages users of earlier versions to upgrade to maintain optimal performance and benefit from continued bug fixes and feature additions planned for future versions.