`outputs.releases_created` has different behavior compared to v3

### TL;DR

I am working on a monorepo.
When in v3 `if: ${{ steps.release.outputs.releases_created }}` can be used to run a step conditionally.
But it doesn't work in v4.
Now I need to use `if: ${{ steps.release.outputs.releases_created == 'true' }}`

### Expected behavior

`if: ${{ steps.release.outputs.releases_created }}` can skip steps.

### Observed behavior

Steps should be skipped always run.

### Action YAML

```yaml
on:
push:
branches:
- main
paths:
- 'packages/**'

name: release

jobs:
release-please:
runs-on: ubuntu-latest
steps:
- uses: google-github-actions/release-please-action@v4
id: release
with:
target-branch: main
- uses: actions/checkout@v4
- uses: actions/setup-node@v4
with:
node-version: 20
registry-url: https://npm.pkg.github.com/
- uses: pnpm/action-setup@v2
with:
version: 8
- run: pnpm i
if: ${{ steps.release.outputs.releases_created }}
- run: pnpm run build
if: ${{ steps.release.outputs.releases_created }}
- name: publish to registry
run: pnpm run publish:all
if: ${{ steps.release.outputs.releases_created }}
env:
NODE_AUTH_TOKEN: ${{secrets.GITHUB_TOKEN}}
```

### Log output

_No response_

### Additional information

Maybe this is not a bug, but it's not mentioned in the migration guide. Maybe we can add something about this.
Also, [manifest-releaser](https://github.com/googleapis/release-please/blob/main/docs/manifest-releaser.md#using-with-github-actions-and-lerna) should be updated.

Compare the v3 and v4 release output documentation, then inspect the migration guide and docs/manifest-releaser.md section linked in the issue. Document the changed conditional-expression behavior and update the manifest-releaser guidance so the v4 usage is clear; verify the examples remain valid GitHub Actions YAML.

Written by the indexing model from the issue text.