[BUG] Sporadic timeouts for prop_MergingTree

[jorisdral]

Describe the bug
prop_MergingTree times out sporadically on GHA CI.

To Reproduce
cabal run lsm-prototypes-tests -- -p 'prop_MergingTree'. It's only sporadically timing out though, so probably one would have to try a few times to see it happen.

Expected behavior
Test should not time out.

Output

https://github.com/IntersectMBO/lsm-tree/actions/runs/13286590286/job/37096606225

Desktop (please complete the following information):
I've seen the timeout happen a few times, and I think it's not linked to a particular OS or GHC version.

Additional context
A likely culprit for tests timing out is a loopy shrinker. There are a few to verify this, for example

• Run the test with --quickcheck-shrinks=0 to prevent shrinking, and see if the test fails without timing out.
• Write tests for generators/shrinkers

If it's not the shrinker, then I'm not sure what the cause could be, since I don't know the tests very well (@mheinzel and @dcoutts probably do)