Trim down vscode test steps

We might want it for a release workflow, but let's save the CI
minutes for pull requests.

.github/workflows/ci.yml

@@ -75,21 +75,10 @@ jobs:
       - uses: actions/setup-node@v4
         with: { node-version: "${{ env.DEFAULT_NODE_VERSION }}" }
 
-      - name: Update npm for attestation feature
-        run: npm install -g npm@latest
-
       - name: Install dependencies
         run: npm clean-install
         working-directory: extension
 
-      - name: Verify the integrity of provenance attestations and registry signatures for installed dependencies
-        run: npm audit signatures
-        working-directory: extension
-
-      - name: Build extension
-        run: npm run build
-        working-directory: extension
-
       - name: Run extension tests in simulated X environment
         run: xvfb-run -a npm run test
         if: runner.os == 'Linux'