Fix flakey tests and improve the test log output

[wallrj]

I've been trying to fix the flakiness in the pull-cert-manager-approver-policy-verify tests:

• https://prow.build-infra.jetstack.net/job-history/gs/jetstack-logs/pr-logs/directory/pull-cert-manager-approver-policy-verify

The tests originally attempted to delete the test namespace after each test, but this can't work because envtest doesn't provide the controller responsible for garbage collection of namespaced resources:

• Can't delete namespaces from test environment kubernetes-sigs/controller-runtime#880

[wallrj]

@inteon I remember you writing some code which watches until a Namespace has actually been deleted.
I think that would help here, because I think root cause of the flakiness is that the next test and its controller-runtime manager are starting up before the Namespace of the previous test has been fully deleted, and reconciling the resources associated with that previous test.

Meanwhile I will try using Eventually to periodically check that the resources have all been deleted.

[wallrj]

The logs are much more readable now:

• https://prow.build-infra.jetstack.net/view/gs/jetstack-logs/pr-logs/pull/cert-manager_approver-policy/166/pull-cert-manager-approver-policy-verify/1600146755117125632

[inteon]

Thank you for fixing the namespace issue.
All test are passing and all resources are removed between tests.
/lgtm

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