Do not create pipeline when the push is authorised for CI JOB token

What does this MR do and why?

This MR prevents CI pipelines from being created when commits are pushed using CI JOB TOKEN authentication. This addresses potential infinite pipeline loops and security concerns where CI jobs could trigger additional pipelines. Changes Made

Core Implementation

Authentication Context Propagation: Added authentication_context parameter throughout the git push flow to track authentication method and build ID

Gitaly Context Handling: Implemented gitaly_context parameter passing from Workhorse → Rails to identify CI job-initiated pushes

Pipeline Prevention: Added validation in Gitlab::Ci::Pipeline::Chain::Validate::Abilities to block pipeline creation when glBuildId is present

Fixes #475705 (closed)

How to set up and validate locally

1. In rails console enable the feature flag

   Feature.enable(:allow_push_repository_for_job_token)

2. Select a project and goto Setting -> CI/CD settings -> Job token permissions

3. Check Allow Git push requests to the repository option

4. Add following .gitlab-ci.yml

stages:
 - update
update-readme:
 stage: update
 image: alpine:latest
 before_script:
 - apk add --no-cache git
 - git config --global user.email "ci@example.com"
 - git config --global user.name "GitLab CI"
 - git remote set-url origin "https://gitlab-ci-token:${CI_JOB_TOKEN}@gdk.test:3000/${CI_PROJECT_PATH}.git"
 script: |
   [ "$EXIT_LOOP_NOW" = "1" ] && exit 1 || true
   echo -e "\n## Update $(date)" >> README.md
   git add README.md
   git commit -m "Update README.md with date"
   git config --global http.sslVerify false
   git push origin HEAD:$CI_COMMIT_REF_NAME -v

1. Make sure that the commits from CI doen't create subsequent pipelines

Screenshots or screen recordings

Before	After

How to set up and validate locally

MR acceptance checklist

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