chore: migrate e2e test repos from openshift-pipelines to tektoncd org

[chmouel]

Context

Several auxiliary repositories used by PAC e2e tests are currently hosted under openshift-pipelines. These need to be transferred to the tektoncd org as part of the migration.

Repos to transfer

• openshift-pipelines/pipelines-as-code-e2e-tests
• openshift-pipelines/pipelines-as-code-e2e-tests-webhook
• openshift-pipelines/pipelines-as-code-e2e-tests-private
• openshift-pipelines/startpaac
• openshift-pipelines/pac-demo

Code changes after transfer

Update .github/workflows/e2e.yaml:

• Line 70 & 391: TEST_GITHUB_PRIVATE_TASK_URL — update URL prefix openshift-pipelines/ → tektoncd/
• Line 72 & 393: TEST_GITHUB_REPO_OWNER_GITHUBAPP: openshift-pipelines/pipelines-as-code-e2e-tests → tektoncd/pipelines-as-code-e2e-tests
• Line 73 & 394: TEST_GITHUB_REPO_OWNER_WEBHOOK: openshift-pipelines/pipelines-as-code-e2e-tests-webhook → tektoncd/pipelines-as-code-e2e-tests-webhook
• Line 318: repository: openshift-pipelines/startpaac → tektoncd/startpaac
• Line 74: TEST_GITHUB_REPO_INSTALLATION_ID: 30347349 — update to the new tektoncd GitHub App installation ID

Notes

• Repo transfers preserve stars, issues, and PRs but update the canonical URL — existing clones will redirect automatically.
• The GitHub App installation ID is tied to the org; it will change once the app is re-authorized under tektoncd.