Run_NeverExceedsMaxParallelism_ButReachesIt asserted two 200 ms solves
overlapped, which depends on the thread pool adding a second worker in
time; hosted Windows release run 39400265218 saw only one. Each fake solve
now waits (up to 10 s) until two solves have entered, so a parallel runner
always reaches the limit and a serial one fails once after the timeout.
Forcing MaxDegreeOfParallelism = 1 fails it (Expected 2, Actual 1).
Project Memory b534b51c.