Use .nvmrc and avoid installing nvm in container since we only need node & npm there. (#2499)

.github/workflows/ci.yml

@@ -132,7 +132,7 @@ jobs:
       - name: Set up Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: 20
+          node-version-file: .nvmrc
 
       - name: Install Node.js dependencies
         run: npm ci