[CI] Fix bot-cherry-pick: use state == "MERGED" instead of invalid merged field (#25987)

.github/workflows/bot-cherry-pick.yml

@@ -89,13 +89,12 @@ jobs:
           PR_URL=""
 
           if [[ -n "$PR_NUMBER" ]]; then
-            if ! PR_JSON=$(gh pr view "$PR_NUMBER" --repo "$GITHUB_REPOSITORY" --json state,merged,mergeCommit,title,number,url); then
+            if ! PR_JSON=$(gh pr view "$PR_NUMBER" --repo "$GITHUB_REPOSITORY" --json state,mergeCommit,title,number,url); then
               echo "::error::Failed to fetch PR #$PR_NUMBER from $GITHUB_REPOSITORY (see gh output above)."
               exit 1
             fi
-            MERGED=$(jq -r '.merged' <<<"$PR_JSON")
             STATE=$(jq -r '.state' <<<"$PR_JSON")
-            if [[ "$MERGED" != "true" ]]; then
+            if [[ "$STATE" != "MERGED" ]]; then
               echo "::error::PR #$PR_NUMBER is not merged (state=$STATE). Only merged PRs can be cherry-picked."
               exit 1
             fi