Cert manager upgrade #1869 (#1886)
Cert manager upgrade #1869 (#1886)

* Changed cluster version to k8s 1.13.

* Removed arguments for generic monitored resource.

* Upgraded cert-manager to version 0.8.1 with validating admission controller.

* Switched gke nightly cluster to default k8s version.

kyma-project/test-infra,kyma-project/test-infra,kyma-project/test-infra