On a disaggregated follower, a layered cursor can reopen its stable cursor even though no newer checkpoint has arrived. When a transaction is allowed to advance the stable cursor (for example, when reading at a timestamp), the cursor advances unconditionally without first checking whether the stable checkpoint has actually moved forward.

This results in unnecessary stable cursor reopens, which are wasteful and increase the layered_curs_reopen_stable statistic with no benefit.

Regression introduced by the rework in WT-17679.

Steps to reproduce:

• On a follower, position a layered cursor on the ingest table (not the stable table).
• In a single transaction, perform two operations.
• Observe that the second operation reopens the stable cursor even though no new checkpoint has been picked up.