Fix build without tests.

[dmkozh]

Description

Fix build without tests.

I'm not sure how this worked before, but we had a few unguarded test-only methods that now finally started to actually cause compilation errors.

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 addresses compilation errors that occur when building stellar-core without test support by properly guarding test-only methods and functions with #ifdef BUILD_TESTS preprocessor directives.

• Guards test-only virtual methods (getMutableEnvelope, clearCached, isTestTx) in TransactionTestFrame to match the base class interface
• Reorganizes function definitions and declarations in TxTests.h and TxTests.cpp to separate test-only overloads from production code
• Removes unused #include "config.h" from Backtrace.cpp
• Fixes lambda capture in LoadGeneratorTests.cpp to properly capture the frameSize variable

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/util/Backtrace.cpp	Removes unused config.h include
src/transactions/test/TransactionTestFrame.h	Guards test-only methods (getMutableEnvelope, clearCached, isTestTx) with #ifdef BUILD_TESTS and relocates isTestTx method
src/transactions/test/TransactionTestFrame.cpp	Guards implementations of getMutableEnvelope and clearCached with #ifdef BUILD_TESTS and relocates clearCached implementation
src/test/TxTests.h	Guards test-only function overloads (parallel Soroban variants) with #ifdef BUILD_TESTS
src/test/TxTests.cpp	Reorganizes closeLedger and closeLedgerOn function definitions to separate test-only variants from production code
src/simulation/test/LoadGeneratorTests.cpp	Adds frameSize to lambda capture list to fix undefined reference