Refactor kpack-image-builder tests

The builder info is created in `JustBeforeEach` so that the test could
conifugure its finalizers in `BeforeEach`. This is to address a flake in
the test when the builder info is being deleted, e.g
https://ci.korifi.cf-app.com/teams/main/pipelines/main/jobs/run-tests-periodic/builds/21592

While being here,
- refactor the suite to create the test root namespace and start the controller in `BeforeEach`. Thus test could not bother cleaning up.
- remove`Serial` from the builder info controller test
- Simplify the builder info controller test by removing contexts that do
  not contribute changes to the default setup
- Remove test cases that verify that the builder info controller is
  listening on cluster builder eventually deletion. The test verifies
  that the info is reconciled on builder change, no need to check the
  same on cluster builder delete (as from controller's point of view,
  the change type does not really matter)

issue #3743