Remove statement context

[Kanasjnr]

Description

Resolves #5171

This PR removes the redundant StatementContext class and refactors the codebase to use soci::statement handles directly.

Rationale

StatementContext was originally an RAII wrapper for std::shared_ptr<soci::statement>, primarily serving the prepared statement cache. Since the cache was removed in #5094, the custom wrapper no longer provides additional benefit. soci::statement is its own handle-based class with internal reference counting, making it the idiomatic way to manage SQL statements when no custom metadata is required.

Changes

• Deleted StatementContext definition from src/database/Database.h.
• Updated Database::getPreparedStatement to return soci::statement by value.
• Refactored all call sites (Ledger, Herder, Overlay, Database, and Tests) to use the soci::statement directly, removing all .statement() calls.
• Verified that resource lifecycle and cleanup are correctly handled by the underlying SOCI library.

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

Verification Proof

• Database Tests: src/stellar-core test "[db]" PASSED.
• Ledger Tests: src/stellar-core test "[ledger]" PASSED.
• Herder Tests: Persistence tests for dead node detection PASSED.
• Grep Audit: Confirmed 0 remaining instances of StatementContext in src/.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[Kanasjnr]

@drebelsky Kinfdly help review

[Copilot]

Pull request overview

This PR removes the redundant StatementContext wrapper and standardizes prepared-statement usage across Stellar Core by returning and using soci::statement handles directly from Database::getPreparedStatement.

Changes:

• Deleted StatementContext and changed Database::getPreparedStatement to return soci::statement by value.
• Refactored SQL call sites to operate directly on the returned soci::statement (remove .statement() indirection).
• Updated affected helper function signatures (e.g., offer-loading helpers) to accept soci::statement&.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/overlay/PeerManager.cpp	Updated peer DB queries to use soci::statement directly.
src/overlay/BanManagerImpl.cpp	Updated ban table queries to use soci::statement directly.
src/main/PersistentState.cpp	Updated persistent state DB reads/writes to use soci::statement directly.
src/ledger/LedgerTxnOfferSQL.cpp	Updated offer SQL loading/upsert/delete paths and helper signatures to use soci::statement directly.
src/ledger/LedgerTxnImpl.h	Updated declarations to match new soci::statement& offer-loading signatures.
src/ledger/LedgerHeaderUtils.cpp	Updated ledger header insert/load statements to use soci::statement directly.
src/herder/test/HerderTests.cpp	Updated test query iteration to use soci::statement directly.
src/herder/HerderPersistenceImpl.cpp	Updated SCP history persistence queries to use soci::statement directly.
src/database/test/DatabaseTests.cpp	Updated migration test helpers/queries to use soci::statement directly.
src/database/Database.h	Removed StatementContext; changed getPreparedStatement API to return soci::statement.
src/database/Database.cpp	Implemented getPreparedStatement returning a prepared soci::statement by value.

[Kanasjnr]

@drebelsky pinging you on this again