Include stdout and stderr in the failure message when the acceptance test fails to match an expected regexp for build failures.
Include stdout and stderr in the failure message when the acceptance test fails to match an expected regexp for build failures.

PiperOrigin-RevId: 313676708
Change-Id: I79e5a62f670a457c13c3eb85c7a0a5b8e19d7de1

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