[analysis] Update MonteCarlo to use Parallelism API

[jwnimmer-tri]

+@calderpg-tri for feature review, please.

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This change is 

[calderpg-tri]

Reviewed 5 of 5 files at r1, all commit messages.
Reviewable status: 1 unresolved discussion, LGTM missing from assignee calderpg-tri, needs platform reviewer assigned, needs at least two assigned reviewers

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systems/analysis/test/monte_carlo_test.cc line 292 at r1 (raw file):

                       num_samples, &generator, kNoConcurrency);
  MonteCarloSimulation(make_simulator, &GetScalarOutput, final_time,
                       num_samples, &generator, kUseHardwareConcurrency);

It probably doesn't matter for such a simple test system, but note that this will use more threads than before (and more than are specified in the test rule).

[jwnimmer-tri]

+@sherm1 for platform review per schedule, please.

Reviewable status: 1 unresolved discussion, LGTM missing from assignees calderpg-tri,sherm1(platform)

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systems/analysis/test/monte_carlo_test.cc line 292 at r1 (raw file):

Previously, calderpg-tri wrote…

It probably doesn't matter for such a simple test system, but note that this will use more threads than before (and more than are specified in the test rule).

Good point, that was doing more harm than good.

[calderpg-tri]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: LGTM missing from assignee sherm1(platform)

[sherm1]

Platform with one ignorable suggestion

Reviewed 4 of 5 files at r1, 1 of 1 files at r2, all commit messages.
Reviewable status: 1 unresolved discussion

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bindings/pydrake/systems/analysis_py.cc line 404 at r2 (raw file):

                          -> std::vector<RandomSimulationResult> {
          return MonteCarloSimulation(make_simulator, output, final_time,
              num_samples, generator, /* parallelism = */ Parallelism::None());

BTW the /* parallelism = */ comment seems superfluous here (would make sense if using the false abbreviation)

[jwnimmer-tri]

Reviewable status: complete! all discussions resolved, LGTM from assignees calderpg-tri,sherm1(platform)

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bindings/pydrake/systems/analysis_py.cc line 404 at r2 (raw file):

Previously, sherm1 (Michael Sherman) wrote…

BTW the /* parallelism = */ comment seems superfluous here (would make sense if using the false abbreviation)

Fair, but for my taste I like highlighting the pseudo-py::arg name here, as a kind of placeholder, grep target, etc. Omitting a kwarg in a binding is quite unusual, so the more I can do to help call attention to the oddity, the better (I hope).