Add Continuous Vulnerability Scanning to e2e:test-on-cng pipeline

Add configuration for Test::Integration::ContinuousVulnerabilityScanning scenario to test-on-cng/main.gitlab-ci.yml

Progress:

• Added new deployment smocker.rb. This is because Test::Integration::ContinuousVulnerabilityScanning requires QA_MOCK_GITHUB: "true"
• Added config for cng-continuous-vulnerability-scanning in test-on-cng/main.gitlab-ci.yml
• Current plan is to deploy smocker as a part of kind deployment.

Status

• Test ran but failed https://gitlab.com/gitlab-org/gitlab/-/jobs/11972804719 - This is a blocker to complete this issue.