[improve][meta] Upgrade Oxia client to 0.9.4

[merlimat]

Motivation

The Oxia Java client 0.9.x line is a performance-focused set of releases on top of 0.8.0, with no breaking public API changes (each 0.9.x release note states that code built against the prior version keeps compiling):

• 0.9.0 — fewer allocations and less lock contention on the hot read/write paths; batch assembly moved from two dedicated threads per shard to a small shared pool; end-to-end backpressure via a bounded total size of pending operations.
• 0.9.1 / 0.9.2 — SharedResources: many client instances in one JVM can share a background thread pool, gRPC connection pool, shard-assignment stream and batcher threads.
• 0.9.3 / 0.9.4 — rate-adaptive write and read batching with a bounded per-shard in-flight window, so under load operations accumulate into larger requests instead of flooding the server with small RPCs.

Modifications

• Bump oxia from 0.8.0 to 0.9.4 in the Gradle version catalog. oxia-testcontainers stays at 0.7.4 (its latest published version; the two version refs were already decoupled in the 0.8.0 bump).
• Update the two bundled Oxia jar versions in distribution/server/src/assemble/LICENSE.bin.txt. The client's bundled runtime dependencies (slog, caffeine, failsafe) are unchanged between 0.8.0 and 0.9.4, so only the two oxia-client / oxia-client-api jar names change.
• Drop the batchLinger(...) calls in OxiaMetadataStore and OxiaMetadataStoreProvider. batchLinger is a no-op in 0.9.x (batching is adaptive) and is deprecated for removal. maxRequestsPerBatch still honors the configured batchingMaxOperations, so there is no runtime behavior change.

Verifying this change

This change is a dependency upgrade covered by the existing Oxia metadata-store tests (pulsar-metadata MetadataStore*/Oxia* suites and the Oxia integration tests). Compilation, checkstyle, and dependency resolution were verified locally.

Does this pull request potentially affect one of the following parts:

• Dependencies (add or upgrade a dependency)

Upgrades io.github.oxia-db:oxia-client from 0.8.0 to 0.9.4. No public API, wire-protocol, schema, config-default, or metrics changes.