workflows/reviewers: fix downloading eval results when undrafting

To actually download the eval results and then proceed to ping
maintainers after undrafting, the run-id must be specified explicitly.

Because we didn't run with `-o pipefail` up to the last commit, we
didn't notice that this workflow was silently failing with this error:

  jq: error: Could not open file comparison/maintainers.json: No such
file or directory

.github/workflows/reviewers.yml

@@ -62,6 +62,7 @@ jobs:
       # In the more special case, when a PR is undrafted an eval run will have started already.
       - name: Wait for comparison to be done
         uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
+        id: eval
         with:
           script: |
             const run_id = (await github.rest.actions.listWorkflowRuns({
@@ -72,6 +73,8 @@ jobs:
               head_sha: context.payload.pull_request.head.sha
             })).data.workflow_runs[0].id
 
+            core.setOutput('run-id', run_id)
+
             // Waiting 120 * 5 sec = 10 min. max.
             // The extreme case is an Eval run that just started when the PR is undrafted.
             // Eval takes max 5-6 minutes, normally.
@@ -90,6 +93,8 @@ jobs:
       - name: Download the comparison results
         uses: actions/download-artifact@fa0a91b85d4f404e444e00e005971372dc801d16 # v4.1.8
         with:
+          run-id: ${{ steps.eval.outputs.run-id }}
+          github-token: ${{ github.token }}
           pattern: comparison
           path: comparison
           merge-multiple: true