Fix DelayedConstraint calling delegates at double the rate.

[manfred-brands]

Fixes #2841

[manfred-brands]

Not sure what goes on with these build agents:

Assert.That(list.PollCount, Is.LessThanOrEqualTo(10 + 1))
  Expected: less than or equal to 11
  But was:  576

This could only happen if the Stopwatch doesn't increase and the Thread.Sleep doesn't actually sleep.

[manfred-brands]

I don't like my hack for the github runners.
Maybe I missed something.

[stevenaw]

@manfred-brands The last few weeks have been busy for me, but I'll try to get a review in of this in the coming days now that I've got a bit more time.

[stevenaw]

Thanks @manfred-brands . Changes themselves look good. Odd about the github runner. It looks like the run before adding that explicit loop only failed on linux, and the build came with a notice that ubuntu-latest would soon change to 24.02. That change has since happened so I'm going to try pushing a test branch with your last commit removed to see if that works now.

[stevenaw]

It looks like that last commit is still needed for GH runners to pass. I don't have any concerns with this PR as-is, however I'll abstain from merging myself in case someone else wants to take a look.
@manfred-brands feel free to merge as well if you're satisfied