chore: restore library generation workflow

.github/workflows/hermetic_library_generation.yaml

@@ -17,13 +17,31 @@ 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:
-    uses: googleapis/google-cloud-java/.github/workflows/reusable_library_generation.yaml@chore/setup-reusable-workflow
-    with:
-      repo_full_name: ${{ github.event.pull_request.head.repo.full_name }}
-      repository: ${{ github.repository }}
-      base_ref: ${{ github.base_ref }}
-      head_ref: ${{ github.head_ref }}
-    secrets:
-      token: ${{ secrets.CLOUD_JAVA_BOT_TOKEN }}
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      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 }}

generation_config.yaml

@@ -1,5 +1,5 @@
 gapic_generator_version: 2.44.0
-googleapis_commitish: eb4c1ec02412e65c453ef0bfc4347731e64dcc82
+googleapis_commitish: c93b54fa3060c7185f6dc724f0f9ec0c12bc44fc
 libraries_bom_version: 26.44.0
 template_excludes:
   - .gitignore