Update pod delete experiment for workflow metadata

[dwdraju]

This is to fix the error while applying workflow argocd file

The Workflow "v2" is invalid: metadata.labels: Invalid value: "{{workflow.parameters.appNamespace}}_kube-proxy": a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character (e.g. 'MyValue',  or 'my_value',  or '12345', regex used for validation is '(([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?')