feat(cubestore): Use seperate working loop for queue

[ovr]

Hello!

refs #5042

Thanks

[Copilot]

Pull Request Overview

Adds a reusable read/write loop abstraction and applies it to both the core store and the cache queue.

• Introduces RocksStoreRWLoop to encapsulate a blocking Tokio channel and processing loop.
• Refactors RocksStore to use write_operation_impl/read_operation_impl with loop names in spans.
• Updates RocksCacheStore to use a separate rw_loop_queue_cf and adds write_operation_queue/read_operation_queue.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
rust/cubestore/cubestore/src/metastore/rocks_store.rs	Added RocksStoreRWLoop, refactored read/write ops to use it.
rust/cubestore/cubestore/src/cachestore/cache_rocksstore.rs	Added queue-specific RW loop, replaced direct store calls.

Comments suppressed due to low confidence (1)

rust/cubestore/cubestore/src/metastore/rocks_store.rs:808

• [nitpick] The RocksStoreRWLoop struct is public but lacks doc comments. Consider adding /// comments to explain its purpose and usage.

#[derive(Debug, Clone)]