ci: add C++ builder to CI builds
ci: add C++ builder to CI builds

PiperOrigin-RevId: 363434122
Change-Id: I8d690c20bd9c8f6c9aa75fa919f60bf53e12e0b4

GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks