Need to set the default subject identifier as username when registering the application

[Akila94]

In IS 6.0.0 and above versions, the username is not used as the default subject identifier. Instead, the ueserID is used as the subject identifier. But when deploying the consent manager API and when executing Berlin flows, the subject identifier needs to be set as username. Currently, this is instructed in the documentation to configure the subject claim as username accessing the carbon console.

As a solution for this, we can make the useUserIdForDefaultSubject SP property false when registering the application. This needs to be done from the accelerator layer to be applicable for all the toolkits.

[Akila94]

Adding the berlin-toolkit label as well for recognition in the Berlin toolkit issues for the open source community.