Reduce latency and increase cache hits with Regional Tiered Cache

Introduced Regional Tiered Cache as a new layer within the existing Tiered Cache offering. This new layer sits between lower-tier and upper-tier data centers, serving as a regional cache. When a lower-tier cache misses, it first queries the regional tier. If the regional tier also misses, it then queries the upper-tier. The regional tier caches the content, benefiting other lower-tier data centers within the same region. This aims to reduce latency for global traffic by avoiding long-distance fetches to upper-tier data centers, while still reducing origin load. It is available for Enterprise customers using Smart or Custom Tiered Cache topologies.