Added OPA keycloak exception for helm tests

Error: warning: Hook test keycloak/templates/tests/test-ui.yaml failed: admission webhook "validation.gatekeeper.sh" denied the request: [allowed-host-filesystem] HostPath volume {"hostPath": {"path": "/cypress", "type": ""}, "name": "cypress-artifacts"} is not allowed, pod: keycloak-cypress-test. Allowed path: []
[volume-types] The volume type hostPath is not allowed, pod: keycloak-cypress-test. Allowed volume types: ["configMap", "emptyDir", "projected", "secret", "downwardAPI", "persistentVolumeClaim"]