[Draft] Replace database-backed getLedgerEntries with high-performance Core server

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What

This introduces STELLAR_CAPTIVE_CORE_HTTP_QUERY_PORT, enabling a high-performance HTTP server on the Captive Core subprocess for fetching ledger entries.

This new endpoint is plumbed all the way through the getLedgerEntries handler, removing those database queries entirely.

This also updates the stellar/go monorepo reference and its cascading dependencies.

Why

With CAP-66 arriving in Protocol 23 and its high-performance /getledgerentry endpoint (whose client was implemented in stellar/go#5542), we don't need to store ledger entries in RPC anymore.

Today, we still need to provide snapshots to the simulation library, but tomorrow (in the opaque sense) we won't need to, so this is part of the transition work.

Related: #269.

Known limitations

TODO:

• Ensure that the correct captive core configuration is generated to enable the server, per details in Add state archival getledgerentry endpoint stellar-core#4623.
• Integration testing

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@2opremio this should probably target a new feature branch e.g. protocol-23 🙏