chore: use workflow in google-cloud-java

.github/workflows/hermetic_library_generation.yaml

@@ -17,31 +17,10 @@ name: Hermetic library generation upon generation config change through pull req
 on:
   pull_request:
 
-env:
-  HEAD_REF: ${{ github.head_ref }}
-  REPO_FULL_NAME: ${{ github.event.pull_request.head.repo.full_name }}
-  GITHUB_REPOSITORY: ${{ github.repository }}
-
 jobs:
   library_generation:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: googleapis/google-cloud-java/.github/workflows/hermetic_library_generation.yaml@main
       with:
-        fetch-depth: 0
         token: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}
-    - name: Generate changed libraries
-      shell: bash
-      run: |
-        set -ex
-        if [[ "${GITHUB_REPOSITORY}" != "${REPO_FULL_NAME}" ]]; then
-          echo "This PR comes from a fork. Generation will be skipped"
-          exit 0
-        fi
-        [ -z "$(git config user.email)" ] && git config --global user.email "[email protected]"
-        [ -z "$(git config user.name)" ] && git config --global user.name "cloud-java-bot"
-        bash .github/scripts/hermetic_library_generation.sh \
-          --target_branch ${{ github.base_ref }} \
-          --current_branch $HEAD_REF
-      env:
-        GH_TOKEN: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}