New Pipeline queuing allows duplicate runs / requests

[Trenly]

With the new pipeline deployment, the queuing doesn't check to see if a request for the same PR is already in the queue. This allows for a single PR to have two runs going concurrently.

I'd expect that if a run is already queued or running, the older request would be removed from the queue and/or the current run would be cancelled.

#242242

[Trenly]

[Policy] Issue Bug
[Policy] Area Validation Pipeline