ci: revert - add a final dd-gitlab/finished job (#10307) (#10353)

This reverts commit e94ed60.

This is now included in the shared pipeline template, we do not need to
define it in our repo.

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [ ] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

.gitlab-ci.yml

@@ -56,16 +56,3 @@ deploy_to_di_backend:manual:
     UPSTREAM_COMMIT_AUTHOR: $CI_COMMIT_AUTHOR
     UPSTREAM_TAG: $CI_COMMIT_TAG
     UPSTREAM_PACKAGE_JOB: build
-
-
-# Final step which only runs when a pipeline has finished successfully.
-# This gives us something block on/wait for in GitHub
-finished:
-  image: registry.ddbuild.io/images/mirror/library/alpine:3.19.3
-  tags: [ "arch:amd64" ]
-  stage: .post
-  rules:
-    - when: on_success
-  script:
-    # TODO: Can we get this to reflect the status from the whole pipeline?
-    - exit 0