Testing: More component tests for Keptn Operator

[RealAnna]

At the moment the component tests only make assertions over appController:

1. KeptnAppController should update the status of the CR ✓
2. KeptnAppController should update the spans ✓
3. [Feature:Performance] Load KeptnAppController should create the app version CR ✓

We should have component test for all controllers and for the webhook.

The current testing framework might have concurrency problems in the existing tests.

Acceptance Criteria

Implement the following tests:

• List specs for each controller
• Translate specs into tests
• List specs for webhook
• Add webhook tests

DoD

• More component tests are present