prevent RUNNING -> RUNNING for autonomous task runs

[zzstoatzz]

This PR adds an AutonomousTaskPolicy that includes a new PreventRunningToRunningTransitions rule to be conditionally applied for autonomous task runs.

Similar to the idea behind #9447, this is primarily to address potential race conditions where the same task run is picked up by more than one TaskServer and submitted to the engine.

Since task runs are created in Pending and transitioned to Running by the engine, we should gracefully abort any subsequent attempt to transition an already Running task run into Running.

Example

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