Timers executed twice during rebalance

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There is a race condition that can happen during a rebalance that will result in a timer being executed twice.

During a rebalance, all of the in-memory timers are cancelled and purged from storage. However, because transports don't have any knowledge of a shutdown or rebalance, a timer executes before it is cancelled or determined to be moved, it will be executed locally on the node, and on the remote node when it arrives.