Disable auto-assignment for Aircall calls

Problem
Aircall calls are automatically assigned when routed to Front, which hides them from the shared inbox view and separates them from Aircall invoice tracking. Teams must manually unassign calls to maintain visibility and proper invoicing.

Request
Disable auto-assignment for Aircall calls so they remain visible in the shared inbox and can be tracked properly in Aircall invoicing, allowing teams to manage assignment manually.