[elasticsearch] fix helm test command

[jmlrt]

• remove wrong --namespace argument
• add --cleanup to clean test pod

$ helm upgrade --wait --timeout=900 --install --values values.yaml helm-es-docker-for-mac ../../
Release "helm-es-docker-for-mac" does not exist. Installing it now.
NAME:   helm-es-docker-for-mac
LAST DEPLOYED: Mon Apr  6 15:57:23 2020
NAMESPACE: default
STATUS: DEPLOYED

...

NOTES:
1. Watch all cluster members come up.
  $ kubectl get pods --namespace=default -l app=elasticsearch-master -w
2. Test cluster health using Helm test.
  $ helm test helm-es-docker-for-mac --namespace=default

$ helm test helm-es-docker-for-mac --namespace=default
Error: unknown flag: --namespace

• Chart version not bumped (the versions are all bumped and released at the same time)
• README.md updated with any new values or changes
• Updated template tests in ${CHART}/tests/*.py
• Updated integration tests in ${CHART}/examples/*/test/goss.yaml

[Conky5]

LGTM