Security Demo relies unnecessarilly on spiffe-helper

[azdagron]

The Identity Management Using SPIRE for Kubeedge demo places the spiffe-helper between Ghostunnel and SPIRE agent in order to allow Ghostunnel to consume resources off of the SPIFFE Workload API. While this was necessary in the past, Ghostunnel has had first-class support for the SPIFFE Workload API since the middle of 2019.

The architecture of the demo can be simplified greatly by removing the spiffe-helper and configuring Ghostunnel to use the SPIFFE Workload API directly.

https://github.com/ghostunnel/ghostunnel/blob/master/docs/SPIFFE-WORKLOAD-API.md