[fix][functions] Fix K8S download function method with auth enabled

[nicoloboschi]

Motivation

After dab0d1f#diff-534a0ee16ee831fd0f16fa1230ff3a6e24f6428abd378790f821867f2ec1ffb0R891 , functions deployed with KubernetesRuntimeFactory doesn't work if the authentication is enabled between components.

Was passed main parameter '--auth-plugin' but no main parameter was defined in your arg class
Download File Data from Pulsar
Usage: download [options]
  Options:
    --destination-file
      The file to store downloaded content
    --fqfn
      The Fully Qualified Function Name (FQFN) for the function
    --name
      The name of a Pulsar Function
    --namespace
      The namespace of a Pulsar Function
    --tenant
      The tenant of a Pulsar Function
    --transform-function
      Download the transform Function of the connector
      Default: false

Note that this regression is only on current master branch.

Modifications

• Set the auth options as pulsar-admin CLI commands instead of functions download options
• Added a test

• doc-not-needed

[eolivelli]

Very good.