Enhance CI local test runner to use SPIRE overlay build system

[saiakhil2012]

Summary

Streamlines our integration testing by aligning test_control_plane.sh with the SPIRE overlay build architecture. This enhancement ensures seamless testing workflows in both CI and local development environments without requiring CI-specific workarounds.

Motivation

As we've modernized our SPIRE integration to use the overlay system (introduced in commit dba010be), our testing infrastructure needed alignment to work naturally with the new build outputs. This change makes local testing workflows match CI behavior without additional setup steps.

Changes

Binary Path Updates

• Before: Expected binaries at hybrid-cloud-poc/spire/bin/spire-server
• After: Uses actual build output at build/spire-binaries/spire-server
• Benefit: No CI symlink workarounds needed

Build System Integration

• Before: Attempted to build with legacy Makefile in hybrid-cloud-poc/spire/
• After: Invokes scripts/spire-build.sh (overlay build system)
• Benefit: Consistent build process across all environments

Smarter Rebuild Detection

• Before: Checked if .go files changed in source tree
• After: Checks if overlay patches modified
• Benefit: Faster detection, aligned with overlay architecture

Improved Diagnostics

• Enhanced error messages with clearer troubleshooting steps
• Build logs saved to /tmp/spire-overlay-build.log for debugging
• Better guidance for manual recovery

Testing

Verified on:

• ✅ Fresh clones (no pre-existing build artifacts)
• ✅ Existing workspaces with prior builds
• ✅ CI environment compatibility maintained
• ✅ Manual python ci_test_runner.py execution

Backward Compatibility

This change maintains compatibility with existing CI workflows. The .github/workflows/ci.yml symlink creation steps can now be considered optional (kept for extra safety) since tests work directly with overlay build outputs.

Commands to Test

# Clean start from repo root
rm -rf build/
./scripts/spire-build.sh

# Run integration tests - now works without symlinks!
cd hybrid-cloud-poc
python ci_test_runner.py

Impact

• Developers: Can run integration tests immediately after building with overlay system
• CI: Continues to work as before, symlink workaround now redundant
• Maintenance: Simpler test infrastructure aligned with modern build system

Checklist

• Code changes tested locally
• CI workflows verified compatible
• Error messages improved for debugging
• No breaking changes to existing workflows
• Commit message follows conventional format

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Commit: 0aa13eae - "Enhance CI test runner to use SPIRE overlay build system"