Add CI to allow Container Scanning to run a test offline

What does this MR do?

CI update for a test to run Container Scanning offline

CI:

• Installs Docker
• Runs a local registry
• Proves connectivity is currently available
• Sets up the Integration test while connectivity is available
• Use IPTables to cut connectivity
• Prove connectivity is not available
• Run a Container Scan (if it fails at this point the job fails)
• Run an Integration Test

What are the relevant issue numbers?

Add offline tests for Container Scanning (gitlab-org/gitlab#404557 - closed)