Intent of TestAssign_NamespaceNotFound

All 3 exact tests in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 3 tests
- server/ 3 tests
  - service/ 3 tests
    
    history/ 3 tests
    
    queues/ 3 tests
    
    TestPriorityAssignerSuite/ 3 tests
    
    go.temporal.io/server/service/history/queues/TestPriorityAssignerSuite/TestAssign_ActiveNamespaceHighPriority Inherited TestAssign_HighPriorityTaskTypes, TestAssign_ActiveNamespaceHighPriority
    
    go.temporal.io/server/service/history/queues/TestPriorityAssignerSuite/TestAssign_HighPriorityTaskTypes Inherited TestAssign_HighPriorityTaskTypes, TestAssign_ActiveNamespaceHighPriority
    
    go.temporal.io/server/service/history/queues/TestPriorityAssignerSuite/TestAssign_NamespaceNotFound Introduced here