feat: update release pipeline to clone from oci bucket

[anithapriyanatarajan]

Changes

This pull request introduces support for drafting Tekton releases using artifacts stored in Oracle Cloud Storage (OCI), in addition to the existing GitHub-based workflow. The changes include:

• Documentation update for using the new release-draft-oci pipeline to draft releases from Oracle Cloud Storage buckets, including instructions for configuring credentials and bucket paths in tekton/resources/release/README.md.
• Added a new Tekton pipeline (release-draft-oci) and supporting task (create-draft-release-oci) in tekton/resources/release/base/github_release_oci.yaml to automate the process of downloading release manifests from OCI, generating release notes, and creating GitHub draft releases.
• Added new Task (prerelease-checks-oci.yaml) that checks for presence of manifets version in oci bucket. The main consideration for pipelines consuming this task is users MUST pass the workspace reference to secret that includes the oci credentials for the cli to connect to the cluster.

    - name: precheck
      runAfter: [git-clone]
      taskRef:
        name:prerelease-checks-oci
      params:
        - name: package
          value: $(params.package)
        - name: versionTag
          value: $(params.versionTag)
        - name: releaseBucket
          value: $(params.releaseBucket)/$(params.repoName)
      workspaces:
        - name: source-to-release
          workspace: workarea
          subPath: git
        - name: oci-credentials
          workspace: release-secret

• Updated tekton/resources/release/base/kustomization.yaml to include the new github_release_oci.yaml resource, ensuring the new pipeline and task are deployed.

/kind misc

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[anithapriyanatarajan]

@afrittoli @AlanGreene @vdemeester - This PR introduces a new pipeline release-draft-oci and task create-draft-release-oci that download release artifacts from Oracle Cloud Storage buckets instead of Google Cloud Storage.
To support a gradual migration:

• Both GCS (release-draft) and OCI (release-draft-oci) versions could be maintained in parallel
• Once all tektoncd repositories and their release cheat sheets are updated with OCI bucket configurations, we can deprecate and remove the GCS version
  This allows teams to migrate at their own pace without disrupting existing release processes.

[anithapriyanatarajan]

/hold

[anithapriyanatarajan]

Marking it hold since the workspace has write permission issues while using the oci-cli conatiner image . This necessitated the need for adding
taskRunTemplate: podTemplate: securityContext: fsGroup: 1000
This is beacuse the download task definition has this added. Evaluating the implication of removing this. Once this is clarified would remove the hold on this PR

[anithapriyanatarajan]

/hold cancel

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[afrittoli]

/lgtm