8.7.15

🐛 Bug Fixes

• 0055a29 - ci: transform release branch names to base branch for Helm chart lookup (commit by @vringar)
• 7963437 - ci: use stable/ prefix in helm-git-refs.json for branch lookup (commit by @vringar)
• c6f3346 - ci: add explicit image-source parameter to INTEGRATION_TEST workflow (PR #6021 by @vringar)

🔧 Chores

• e56b93e - use hardened base images for 8.7 (PR #6079 by @chillleader)