chore: remove unused cache from sandbox catalog

[jakubno]

Remove local cache from redis, it wasn't really used anywhere

[cursor]

PR Summary

Medium Risk
Medium risk because this increases Redis read/write traffic and removes a short-lived read-through cache, which could impact latency or load under high request rates. Behavioral correctness should be unchanged, but performance characteristics may shift in production.

Overview
This PR removes the optional local TTL cache from the Redis-backed sandbox catalog and simplifies NewRedisSandboxCatalog to take only a Redis client, updating the orchestrator and client-proxy call sites accordingly. It also deletes the noop/cache implementations and the associated cache-focused tests, leaving all sandbox catalog operations to read/write directly against Redis.

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