devcontainer test feature should print failed scenario

# Observation

When running `devcontainer features test --skip-autogenerated . --features sphinx-needs` and one scenario fails to install, I get an error like this:

```
ERROR: failed to solve: executor failed running [/bin/sh -c cd /tmp/build-features/sphinx-needs_1 && chmod +x ./devcontainer-features-install.sh && ./devcontainer-features-install.sh]: exit code: 1
[-] Failed to launch container:

Command failed: docker buildx build --load --build-context dev_containers_feature_content_source=/tmp/devcontainercli-root/container-features/0.19.1-1666518600028 --build-arg _DEV_CONTAINERS_BASE_IMAGE=openjdk:11-jre-slim-buster --build-arg _DEV_CONTAINERS_IMAGE_USER=root --build-arg _DEV_CONTAINERS_FEATURE_CONTENT_SOURCE=dev_container_feature_content_temp --target dev_containers_target_stage -t vsc-1666518596856-a120028da78526213f1f43b6b286e042-features -f /tmp/devcontainercli-root/container-features/0.19.1-1666518600028/Dockerfile.extended /tmp/devcontainercli-root/empty-folder
```

# Expectation

None of the output above is actually helpful to me.
Some hint wich scenario failed would be nice, e.g. "Scenario java_preinstalled_no_options has failed".
And a simple and readable statement like "sphinx-needs/install.sh failed with exit code 1".