Allow Azure Key Vault conformance test use environment variable for vaultName

[CodeMonkeyLeet]

Describe the proposal

Unlike the other conformance tests, the azure-keyvault.yaml config hardcodes the name of the target resource which creates an issue for contributors wanting to set up their own test environments. For example, different users sharing an Azure subscription may not be able to manage the permissions on the fixed name key vault individually, and will need to edit the yaml to retarget against their own keyvault instance. This also creates a stumbling block for any automation to facilitate contributors setting up their own Azure conformance test environments on demand.

The proposal is to simply update the Azure Key Vault conformance test use environment variable for vaultName in the azure-keyvault.yaml

[CodeMonkeyLeet]

/assign