Use signalR group for local development

[andchiind]

Describe the improvement you would like to see
We currently use groups to distinguish different access rights. We also want to make these even more specific when developing locally so that the group is unique to each local user. This can either be a generated ID or a value set in .env and read from appsettings.

How will this change existing functionality?
It will avoid signalR conflicts in local development.

How will this improvement affect the current Threat Model?
N/A, but don't use personal information to make the group name.