Mention who triggered the release in the release PR (#4753)

* Mention who triggered the release in the release PR

* Search for the PR against the right base

* Use printf -v

Author: dskloetc

.github/workflows/upsert-release-pr.yml

@@ -122,14 +122,13 @@ jobs:
           # trigger other workflows. So we use the token created in the
           # previous step.
           GITHUB_TOKEN: ${{ steps.setup-github-token.outputs.access-token }}
-      - name: Annotate release PR with streams build option
-        if: env.BUILD_STREAMS_ADAPTER_IMAGES == 'true'
+      - name: Annotate release PR description
         env:
           GITHUB_TOKEN: ${{ steps.setup-github-token.outputs.access-token }}
         # We use gh pr list with exact title match instead of --search to avoid GitHub search index lag
         run: |
           PR_NUMBER=$(gh pr list \
-            --base main \
+            --base "${{ github.ref_name }}" \
             --state open \
             --json number,title \
             --jq ".[] | select(.title == \"Release $BUMPED_VERSION\") | .number")
@@ -140,14 +139,22 @@ jobs:
           fi
 
           PR_BODY=$(gh pr view "$PR_NUMBER" --json body --jq '.body')
-          MARKER='<!-- build-streams-adapter-images:true -->'
 
-          if [[ "$PR_BODY" == *"$MARKER"* ]]; then
-            echo "Streams marker already present in PR body"
-            exit 0
+          printf -v PR_BODY_PREFIX "This release was triggered by @%s.\n\n" "${{ github.actor }}"
+          PR_BODY_SUFFIX=""
+
+          if [[ "$BUILD_STREAMS_ADAPTER_IMAGES" = "true" ]]; then
+            MARKER='<!-- build-streams-adapter-images:true -->'
+
+            if [[ "$PR_BODY" == *"$MARKER"* ]]; then
+              echo "Streams marker already present in PR body"
+              exit 0
+            fi
+
+            printf -v PR_BODY_SUFFIX "\n\n## Release Options\n%s\n- [x] Build streams adapter images\n" "$MARKER"
           fi
 
-          UPDATED_BODY=$(printf "%s\n\n## Release Options\n%s\n- [x] Build streams adapter images\n" "$PR_BODY" "$MARKER")
+          printf -v UPDATED_BODY "%s%s%s" "$PR_BODY_PREFIX" "$PR_BODY" "$PR_BODY_SUFFIX"
 
           gh api \
             --method PATCH \