Disable leak test on GCE plugin tests (#35555)
Disable leak test on GCE plugin tests (#35555)

Example failures
https://storage.googleapis.com/istio-prow/logs/unit-tests_istio_postsubmit/1447657175148138496/build-log.txt
istio/istio,istio/istio,istio/istio,istio/istio,istio/istio