Remove unnecessary Node.js setup and npm ci from vulnerability scan

Grype parses package-lock.json directly via Syft's javascript-lock-cataloger.
No need to install node_modules for vulnerability scanning.

Co-authored-by: aviadhahami <7353632+aviadhahami@users.noreply.github.com>
Agent-Logs-Url: https://github.com/nodevault/node-vault/sessions/7ce325a9-9cf4-4429-bd29-0e641afd7023

Author: Copilot

.github/workflows/vulnerability-scan.yaml

@@ -18,14 +18,6 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
 
-      - name: Set up Node.js
-        uses: actions/setup-node@v4
-        with:
-          node-version: 18
-
-      - name: Install dependencies
-        run: npm ci
-
       - name: Scan for vulnerabilities
         uses: anchore/scan-action@v7
         id: scan