Update ecosystem pull request comment to post when unrelated jobs fail (#8289)

While we ran the `pr-comment` workflow on `completed` workflows (i.e.
instead of `success`, it can have failed) we used the default artifact
download behavior which required `success` workflows
(https://github.com/dawidd6/action-download-artifact) which meant that
if any jobs failed the ecosystem checks would not be reported.

For example, a successful ecosystem run at
https://github.com/astral-sh/ruff/actions/runs/6672033727/job/18135290880
was not posted at
https://github.com/astral-sh/ruff/actions/runs/6672153598/job/18135534008
because no artifacts met the success criterion.

You can see this is "valid" with a manual dispatch at
https://github.com/astral-sh/ruff/actions/runs/6672278055/job/18135883849
but it pulls from the latest commit rather than the one with the failed
one mentioned above so you can't see verification it'll work for failed
jobs. Another manual dispatch at
https://github.com/astral-sh/ruff/actions/runs/6672349316/job/18136082917
shows it works great for successful jobs still.

.github/workflows/pr-comment.yaml

@@ -41,6 +41,7 @@ jobs:
           workflow: ci.yaml
           pr: ${{ steps.pr-number.outputs.pr-number }}
           path: pr/ecosystem
+          workflow_conclusion: completed
           if_no_artifact_found: ignore
 
       - name: Generate Comment