fix: simplify coverage report artifact naming by removing node version

.github/workflows/ci-app.yml

@@ -136,7 +136,7 @@ jobs:
       - name: Upload coverage report as artifact
         uses: actions/upload-artifact@v4
         with:
-          name: coverage-node${{ matrix.node-version }}-mongo${{ matrix.mongodb-version }}
+          name: coverage-mongo${{ matrix.mongodb-version }}
           path: |
             apps/app/coverage
             packages/remark-growi-directive/coverage