Add E2E test for GCS log storage

[khrm]

Changes

Fixes #593

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Release Notes

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sayan-biswas

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[khrm]

To see whether there's a flake in this or not /retest pull-tekton-results-integration-tests

[tekton-robot]

@khrm: The /retest command does not accept any targets. The following commands are available to trigger required jobs:

• /test pull-tekton-results-build-tests
• /test pull-tekton-results-integration-tests
• /test tekton-results-unit-tests

Use /test all to run all jobs.

In response to [this](https://github.com/tektoncd/results/pull/591#issuecomment-1706842223): >To see whether there's a flake in this or not >/retest pull-tekton-results-integration-tests Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository.

[khrm]

/test pull-tekton-results-integration-tests

[khrm]

/test pull-tekton-results-integration-tests

[khrm]

/test pull-tekton-results-integration-tests

[khrm]

/test pull-tekton-results-integration-tests

[khrm]

/test pull-tekton-results-integration-tests

[khrm]

I have tested this multiple time and can see that there's no flake.

[khrm]

After merging this, we can do the release. @enarha

[khrm]

Job history. https://prow.tekton.dev/pr-history/?org=tektoncd&repo=results&pr=591

The relevant one is integration tests. The last few runs have been successful continuously.

/test pull-tekton-results-integration-tests

[enarha]

/lgtm