Introduce log read preference for remote-first tiering reads

[zuston]

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Motivation

The motivation of this PR is to reduce TabletServer RPC and local disk pressure when fetching high-throughput logs.

Based on observations from production workloads, when ingestion throughput reaches around 20 GB/s, log fetch traffic from the tiering service can reach about 30 GB/s. This puts significant additional pressure on TabletServers, especially on RPC handling and local disk reads.

Solution

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Anything else?

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Willingness to contribute

• I'm willing to submit a PR!