[VladRodionov]

Summary

This PR continues the BlockCache pluggable architecture work by migrating the remaining HBase callers from the legacy BlockCache API to the new CacheAccessService / CacheEngine abstractions.

The goal is to remove direct dependencies on BlockCache from HBase-facing code while preserving the existing cache behavior and compatibility.

Changes

• Migrated remaining RegionServer cache callers to CacheAccessService.
• Updated cache-related RegionServer diagnostics and web UI code.
• Preserved tier-specific L1/L2 diagnostics through CacheEngine where required.
• Migrated cache-related tests to use CacheAccessService and CacheEngine.
• Updated HBaseTestingUtil and HBaseTestingUtility test infrastructure to inject CacheAccessService instead of BlockCache.
• Updated HeapMemoryManager integration to work with the appropriate resizable cache engine.
• Migrated tests that previously accessed individual caches through BlockCache#getBlockCaches().
• Updated fully-cached-file checks to use the aggregate CacheAccessService#getFullyCachedFiles() API.
• Fixed testPrefetchWhenDataTieringEnabled to re-read the current fully-cached-files state while waiting for asynchronous prefetch completion. TopologyBackedCacheAccessService#getFullyCachedFiles() returns an aggregate snapshot rather than a live backing map.

This change intentionally keeps direct CacheEngine access limited to tests, diagnostics, topology-specific code, and places where per-tier behavior is required. Normal HBase read/write paths use CacheAccessService.

Compatibility

Legacy cache implementations can still participate through the existing BlockCache-to-CacheEngine adapters. This allows the migration to proceed incrementally without requiring all cache implementations to be converted at once.

No user-visible behavior change is intended.

Testing

• mvn package -DskipTests
• Cache-related unit tests in hbase-server
• testPrefetchWhenDataTieringEnabled
• Existing cache package tests