If a checkpoint is configured to flush tables, it needs to do that irrespective of whether that table was meant to participate in the checkpoint process. This ticket will make the necessary changes to ensure a flush tier doesn't get skipped for a table.

The checkpoint process has several inbuilt conditions to entirely skip the checkpoint or skip individual tables if they are clean and need not participate. The clean trees benefit from participating in the checkpoint if there are older checkpoints that could get deleted as part of the process. Since getting the list of older checkpoints could be expensive, WT-6421 added a mechanism to set a timer to check for these tables every 10 mins. Even when the timer expires, a clean table only checkpoints if there are older tables to be deleted. Make sure to account for this logic that skips the checkpoints.