Intent of chatService.test|title=ChatService serializer _previous field does not retain data after model disposal|occurrence=1

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

mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/ 3 tests
- workbench/ 3 tests
  - contrib/ 3 tests
    
    chat/ 3 tests
    
    test/ 3 tests
    
    common/ 3 tests
    
    chatService/ 3 tests
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/workbench/contrib/chat/test/common/chatService/chatService.test|title=ChatService previousModelRef pattern in ChatViewPane does not cause double-reference retention|occurrence=1 Inherited chatService.test|title=ChatService previousModelRef pattern in ChatViewPane does not cause double-reference retention|occurrence=1
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/workbench/contrib/chat/test/common/chatService/chatService.test|title=ChatService serializer _previous field does not retain data after model disposal|occurrence=1 Introduced here
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/workbench/contrib/chat/test/common/chatService/chatService.test|title=ChatService switching between sessions disposes previous models and releases all references|occurrence=1 Inherited chatService.test|title=ChatService switching between sessions disposes previous models and releases all references|occurrence=1