[CI] Use "force_orphan" option of GH action peaceiris/actions-gh-page…

…s@v3

With this change, the API documentation that we generate as part of our CI
will overwrite the `gh-pages` branch, only keeping the latest generated
documentation. This will reduce the repository size (when cloned, from
close to 3GB to ~150M.

As a consequence, we will lose the history of API documentation. It will
still be possible to manually generate it locally (yarn docs).

Fixes #11625

Signed-off-by: Marc Dumais <[email protected]>

.github/workflows/ci-cd.yml

@@ -146,6 +146,7 @@ jobs:
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./gh-pages
+          force_orphan: true    # will only keep latest commit on branch gh-pages
 
       - name: Publish NPM
         uses: nick-invision/retry@v2