Save cache only on pushes to default branch

Author: christophfroehlich

.github/workflows/reusable-industrial-ci-with-cache.yml

@@ -96,8 +96,8 @@ jobs:
         uses: actions/checkout@v4
         with:
           ref: ${{ inputs.ref_for_scheduled_build }}
-      - name: Cache ccache folder
-        uses: actions/cache@v4
+      - name: Restore ccache folder
+        uses: actions/cache/restore@v4
         with:
           path: ${{ env.CCACHE_DIR }}
           key: ccache-${{ env.CACHE_PREFIX }}-${{ github.sha }}-${{ github.run_id }}
@@ -128,6 +128,14 @@ jobs:
           CXX: ${{ inputs.cxx_compiler }}
           CMAKE_ARGS: -DCMAKE_CXX_FLAGS="-isystem /opt/ros/${{ inputs.ros_distro }}/include"
         id: ici
+      - name: Save ccache folder
+        uses: actions/cache/save@v4
+        # but only on default branch to save disk space
+        if: github.ref == format('refs/heads/{0}', github.event.repository.default_branch)
+        with:
+          path: ${{ env.CCACHE_DIR }}
+          key: ccache-${{ env.CACHE_PREFIX }}-${{ github.sha }}-${{ github.run_id }}
+
       - name: Download issue template for target failure  # Has to be a local file
         if: ${{ always() && steps.ici.outcome == 'failure' && github.event_name == 'schedule' }}
         run: