Refactor and Extend CA Tests for better debugabbility, supportability and performance

[elankath]

What would you like to be added:

• Refactor Integration Tests away from Ginkgo and into standard Go tests.
• Make Integration Tests robust
  • Wait for previous test ops to complete fully in the semantic sense - add additional conditions.
  • Assertion data should take into account actual state of cluster
• Extend existing unit and integration tests to cover scaling race conditions between CA and MCM
• Make Integration Tests more convenient to execute
  • Do not mandate the user to manually setup a shoot cluster with exacting worker pool configuration. The test setup should do this by itself or at-least offer a setup script to do this.
  • Remove all issues in supporting local execution of integration tests with local machine-controller-manager and local machine-controller-(aws|gcp|etc).
  • Support local execution of Integration tests with speed, leveraging the machine-controller-virtual

Why is this needed:

• Current Tests are flay and very prone to timining dependent failures
• Current tests have issues in supporting local execution.
• Current Tests are very hard to debug when something goes wrong - primarily due to Ginkgo useability.
• Current Integration Test Setup is deeply inconvenient

From official Go FAQ

A related point is that testing frameworks tend to develop into mini-languages of their own, with conditionals and controls and printing mechanisms, but Go already has all those capabilities; why recreate them? We’d rather write tests in Go; it’s one fewer language to learn and the approach keeps the tests straightforward and easy to understand.