[2.5] Race condition during reconnect can cause websocket to crash and repeatedly disconnect

[Mike Pontillo]

After supending and resuming my laptop while it was connected to MAAS, I noticed a problem that caused the websocket to repeatedly attempt to reconnect. Each time it reconnected, the following exception was raised on the server:

https://paste.ubuntu.com/p/4SqVvZFgkR/

This is a race condition in WebSocketProtocol.authenticated(). Before creating the `self.request`, authenticated() calls processMessages(). The processMessages() method calls handleRequest() -> buildHandler(), which requires the `self.request` (which was not created in __init__() and does not exist yet).