Closed PRs are showing up in the Needs Champion column

[jeffhandley]

Here's an example where closing a PR resulted in adding the PR to the project board, and it was added into the Needs Champion column despite already being closed:
dotnet/runtime#62435

There have been other scenarios like this too. The root cause of this behavior is that we're relying on the built-in project board automation and this isn't working completely because:

1. The Needs Champion column is configured with the To do preset; when a PR is added to the board it lands in this column by default
2. The Done column is configured with the Done preset; when a PR already on the board is closed, it is moved into that column

However, if a PR is already closed when it's added to the board, it lands in the wrong place. To work around this, we will need to move away from the project board automation presets and instead configure FabricBot to prevent the item landing in the wrong column, or use a scheduled search to move items to the Done column if closed.

[jeffhandley]

To fix this, we'll just apply a condition such that PRs won't be added to the project board if they're already closed.