Set Vault URL as variable

Summary

Currenty Sylva deploys a Vault server in the management cluster, then k8s resources, using this vault, are configured with the local URL of the vault, i.e. https://vault.vault.svc.cluster.local:8200. If we want to use an external vault, instead a local one, it must be possible to change the Vault URL.

related references

#2262

Edited by Pierrick Seite