Tweak the release process: no more merge to main (#7994)

.github/actions/generate-release-pr-body/pr_body_template.txt

@@ -7,7 +7,11 @@ Push the release tag to trigger the release:
    git fetch && git tag v{{VERSION}} origin/release/{{VERSION}}
    git push origin v{{VERSION}}
    ```
-This PR will auto-merge once the tag is pushed.
+The tag push will trigger the release build. This PR will be automatically closed.
+
+## Cherry-Picks
+
+If you need to include additional fixes, cherry-pick them into the `release/{{VERSION}}` branch before tagging.
 
 ## Important Notes