Remove [FF] ci_stop_using_has_exposed_artifacts_metadata_col

What does this MR do and why?

Background

A CI pipeline can be configured with "exposed artifacts" using the artifacts:expose_as keyword. These artifacts are listed as file links in the merge request UI with the name set to the expose_as value.

We currently use the column p_ci_builds_metadata.has_exposed_artifacts in the scope .with_exposed_artifacts to find jobs with exposed artifacts in FindExposedArtifactsService. This service iterates through each job where has_exposed_artifacts = true and fetches the applicable artifacts.

As part of our plan to migrate data away from the metadata table (https://gitlab.com/groups/gitlab-com/gl-infra/data-access/dbo/-/epics/36), we need update the code so it's no longer dependent on the has_exposed_artifacts column.

Feature MR

In !195693 (merged), we introduced the feature flag ci_stop_using_has_exposed_artifacts_metadata_col, which implemented the following:

Updates the logic for finding exposed artifacts so it doesn't use the has_exposed_artifacts column. This means that we have to iterate through all latest builds of a pipelines and check each one for exposed artifacts.

The feature flag was globally rolled out in #551510 (comment 2618828878) at 2025-07-10 3:54PM PT. It has been on for a few days and is deemed stable.

This MR

This MR removes the code related to ci_stop_using_has_exposed_artifacts_metadata_col.

References

• Roll-out issue: [FF] `ci_stop_using_has_exposed_artifacts_metad... (#551510 - closed)

How to set up and validate locally

These steps will lead you through creating an exposed artifact and verifying that the feature still works as before.

Prerequisite: Ensure you have a GitLab Runner set up with your gdk.

1. Check out this branch (restart gdk if needed.)

2. Create a new blank project with the following pipeline config:

.gitlab-ci.yml

generate-exposed-artifact:
  script:
    - echo "My test artifact" > my_artifact.txt
  artifacts:
    paths:
      - my_artifact.txt
    expose_as: 'My Test Artifact'

control-job:
  script: echo

3. Commit (anything) to a new branch and open a merge request. In that MR, wait for the pipeline to complete. Then observe that the artifact is correctly exposed in the UI:

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #551510 (closed)