Skaffold child builds using Kaniko fails with the Google Cloud Build integration

Using Skaffold to build an image from a Dockerfile with Kaniko on Google Cloud Build results in a parent build and a child build. The child build succeeds in building the image but the parent build fails with the error message:
```
error copying logs to stdout: invalid write result
ERROR
ERROR: build step 0 "gcr.io/k8s-skaffold/skaffold:v2.11.1" failed: step exited with non-zero status: 1
```
The error is coming from [here](https://github.com/GoogleContainerTools/skaffold/blob/bcd018015a4994a0f4693166728843ec79034a74/pkg/skaffold/build/gcb/cloud_build.go#L223) in the implementation of the GCB builder.

### Expected behavior

The intended functionality is that the Skaffold image would output the child build logs so that they could be surfaced in the parent build logs.

### Actual behavior
The above error.

### Information

- Skaffold version: gcr.io/k8s-skaffold/skaffold:v2.11.1
- Operating system: Google Cloud Build Default Pool VM
- Installed via: Executed as image with the following args to Cloud Build [ "skaffold", "build", "--filename=skaffold.issue.yaml", "--timestamps=true" ]
- Contents of skaffold.yaml:

```yaml
apiVersion: skaffold/v4beta9
kind: Config
metadata:
name: failing-parent-build

build:
googleCloudBuild:
region: asia-southeast1

tagPolicy:
dateTime: {}

artifacts:
- image: asia-southeast1-docker.pkg.dev/test-project/test-repo/test-image
kaniko:
dockerfile: Dockerfile
cache:
cacheCopyLayers: true
verbosity: debug
```
- Contents of cloudbuild.yaml:
```
steps:
- name: gcr.io/k8s-skaffold/skaffold:v2.11.1
args: [ "skaffold", "build", "--filename=skaffold.issue.yaml", "--timestamps=true" ]
```
- Contents of Dockerfile:
```
FROM alpine
COPY quickstart.sh /
CMD ["/quickstart.sh"]
```

### Steps to reproduce the behavior

Steps are based on the Google Cloud Build [quickstart](https://cloud.google.com/build/docs/build-push-docker-image#prepare_source_files_to_build)

1. Copy the above example skaffold.yaml, cloudbuild.yaml and Dockerfile to a directory.
2. Create an empty quickstart.sh file in the same directory. `touch quickstart.sh`
3. Run the command `gcloud builds submit --region=asia-southeast1 --config cloudbuild.issue.yaml`
4. The parent build should successfully download the Skaffold image and create a child build using the image to build the Dockerfile with Kaniko.
5. The parent build will fail when attempting to surface the child build logs from the Skaffold image.