Websocket exponential backoff is not randomized

[drathier]

Websocket reconnect attempts should be spaced out randomly, to spread out any spikes that might have caused the outage in the first place. Otherwise you'll just overload the server again every 2^c seconds.

Ethernet uses a random backoff between 0 and 2^c-1, and we should do something similar.

[process-bot]

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