Update Test Flows to support multiple Holders

[PaulWen]

To scale the holder side we switched from one holder to many holders where each holder has its own wallet.

The load is distributed across the holder by the load generator. The initialization procedure for the following test flows still needs to be updated to support multiple holders. Each holder needs to be provisioned individually before starting the load generation.

• Credential Issuance Flow (Issuer/Verifier needs to initiate a connection with each holder during initialization)
• Proof Request Flow (Issuer/Verifier needs to initiate a connection with each holder during initialization AND issue a credential to each holder)