Lin Thread Queue test reliability

[jmid]

I've seen the Lin Thread Queue test find a counterexample under Windows bytecode in less that 250 attempts more than once.

This happened yesterday on 5.1.0~alpha2 windows bytecode:
https://github.com/ocaml-multicore/multicoretests/actions/runs/5199454489/jobs/9376867328

random seed: 189508584
generated error fail pass / total     time test name

[ ]    0    0    0    0 / 1000     0.0s Lin DSL Queue test with Domain
[ ]    0    0    0    0 / 1000     0.0s Lin DSL Queue test with Domain (generating)
[✓]    2    0    1    1 / 1000     5.1s Lin DSL Queue test with Domain

[ ]    0    0    0    0 /  250     0.0s Lin DSL Queue test with Thread
[✗]   68    0    1   67 /  250    16.8s Lin DSL Queue test with Thread

--- Info -----------------------------------------------------------------------

[...]

--- Failure --------------------------------------------------------------------

Test Lin DSL Queue test with Thread failed (0 shrink steps):

[...]

  Results incompatible with sequential execution

                                               |                    
                           Queue.take t : Error (Stdlib.Queue.Empty)
                                    Queue.take_opt t : None         
                                    Queue.is_empty t : true         
                                    Queue.is_empty t : true         
                                    Queue.is_empty t : true         
                           Queue.take t : Error (Stdlib.Queue.Empty)
                                      Queue.clear t : ()            
                                               |                    
                         .------------------------------------------.
                         |                                          |                    
                Queue.length t : 1                         Queue.add 7 t : ()            
            Queue.take_opt t : Some (7)                Queue.peek_opt t : Some (7)       
                Queue.length t : 1                         Queue.add 1 t : ()            
               Queue.peek t : Ok (4)                       Queue.add 4 t : ()            
               Queue.peek t : Ok (4)                      Queue.peek t : Ok (4)          
              Queue.is_empty t : true                     Queue.peek t : Ok (4)          
     Queue.take t : Error (Stdlib.Queue.Empty)         Queue.take_opt t : Some (4)       
                Queue.clear t : ()                       Queue.take_opt t : None         
                                                           Queue.clear t : ()            

================================================================================
failure (1 tests failed, 0 tests errored, ran 2 tests)

And earlier

• on Don't consider Sys STM tests negative on ARM64 #361 on Windows 5.1 bytecode
• on Document CI testing options #349 on Windows bytecode trunk
• on Add workflows to test OCaml trunk on Cygwin #305 on Windows bytecode trunk