Cleanup historical ledger query

[SirTyson]

Description

This is another follow up in the ledger state refactor.

Currently, CompleteConstLedgerState manages historical snapshots. These are only used by captive-core for the RPC query server, but add complexity to the core LedgerState interface. This PR makes it such that the QueryServer is responsible for maintaining it's own historical states, so CompleteConstLedgerState is simplified to just containing the minimum LCL state.

Checklist

• Reviewed the contributing document
• Rebased on top of master (no merge commits)
• Ran clang-format v8.0.0 (via make format or the Visual Studio extension)
• Compiles
• Ran all tests
• If change impacts performance, include supporting evidence per the performance document

[Copilot]

Pull request overview

This PR continues the ledger state refactor by removing historical snapshot management from ImmutableLedgerData/ImmutableLedgerView and shifting responsibility for retaining historical queryable snapshots to QueryServer (primarily used by captive-core/RPC query server).

Changes:

• Move historical snapshot retention from ImmutableLedgerData/BucketListSnapshot into QueryServer, with a shared snapshot map plus per-thread ImmutableLedgerView caches.
• Wire snapshot publication from LedgerManagerImpl → CommandHandler → QueryServer on ledger close.
• Update/add tests to exercise QueryServer snapshot window behavior and concurrent snapshot access.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/main/test/QueryServerTests.cpp	Switch tests to use CommandHandler’s QueryServer and add snapshot-window coverage (0 snapshots + eviction behavior).
src/main/QueryServer.h	Add shared snapshot store (mStates), per-thread snapshot cache, and test hooks (registerThread, resetForTesting).
src/main/QueryServer.cpp	Implement addSnapshot() and getSnapshotForLedger() and route query lookups through retained snapshots.
src/main/Config.h	Add QUERY_SERVER_FOR_TESTING (tests-only) to allow direct QueryServer usage without network IO.
src/main/CommandHandler.h / src/main/CommandHandler.cpp	Add addSnapshot() forwarding and a test-only QueryServer instantiation path; expose getQueryServer() in tests.
src/main/ApplicationImpl.cpp	Construct CommandHandler earlier so ledger loading can publish snapshots; add test-only QueryServer reset to avoid duplicate-seq assertions.
src/ledger/test/ImmutableLedgerViewTests.cpp	Update stress test to use QueryServer-provided snapshots and register worker threads for per-thread caching.
src/ledger/LedgerManagerImpl.h / src/ledger/LedgerManagerImpl.cpp	Remove historical snapshot plumbing from ledger state construction and publish snapshots to CommandHandler after advancing LCL.
src/ledger/ImmutableLedgerView.h / src/ledger/ImmutableLedgerView.cpp	Remove historical snapshot APIs and historical snapshot storage from ImmutableLedgerData.
src/bucket/test/BucketTestUtils.cpp	Update ImmutableLedgerData::createAndMaybeLoadConfig call signature.
src/bucket/test/BucketIndexTests.cpp	Remove historical snapshot test that depended on the removed historical snapshot API.
src/bucket/BucketListSnapshot.h / src/bucket/BucketListSnapshot.cpp	Remove historical snapshot routing/storage from SearchableBucketListSnapshot; simplify constructors and loads.

[dmkozh]

nit: Can we dedup this with SearchableHotArchiveBucketListSnapshot::loadKeys with a helper?

[SirTyson]

Fixed