Restore accidentally removed webpack bundle cleanup steps in Pro CI

During rebase, the 'Remove old webpack bundles' step and the 'Restore test
webpack bundles from cache' step were accidentally removed from the Pro CI
workflow. These steps are essential for:

1. Cleaning old webpack bundles before tests
2. Restoring cached webpack bundles to speed up CI

This restores both steps to their original position in the workflow.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

.github/workflows/pro-test-package-and-gem.yml

@@ -218,6 +218,22 @@ jobs:
           path: react_on_rails_pro/node_modules
           key: v4-pro-package-node-modules-cache-${{ hashFiles('react_on_rails_pro/yarn.lock') }}
 
+      - name: Remove old webpack bundles
+        run: |
+          rm -rf spec/dummy/public/webpack
+          rm -rf spec/dummy/ssr-generated
+
+      - id: get-sha
+        run: echo "sha=$(git rev-parse HEAD)" >> "$GITHUB_OUTPUT"
+
+      - name: Restore test webpack bundles from cache
+        uses: actions/cache@v4
+        with:
+          path: |
+            react_on_rails_pro/spec/dummy/public/webpack/test
+            react_on_rails_pro/spec/dummy/ssr-generated
+          key: v4-pro-dummy-app-webpack-bundle-${{ steps.get-sha.outputs.sha }}
+
       - name: Install Node modules with Yarn for Pro package
         working-directory: .
         run: |