Migrate Eventing upgrade tests to use new upgrade framework (knative/pkg#1652)

[cardil]

Problem
Eventing upgrade tests should be migrated to utilize new upgrade tests framework (knative/pkg#1652), and remove reliance on huge bash scripting and enable to easily compose tests from reusable operations.

Persona:
Developer

[cardil]

/assign

[zhongduo]

Thanks @cardil . I would love to help test and review once the PR is ready. IIUC, due to the limitation of IMC, we will still ignore the errors in eventing after this, right? This if more for refactoring.

[cardil]

PR is up. Yes. This is a pure refactor to consume new composite friendly test framework.