Use plot directive to generate figures

Currently we have a couple of pngs in the documentation that could be generated by the examples instead, using the `plot` directive. However, it is currently blocked by https://github.com/scientific-python/pytest-doctestplus/issues/219 as we saw in #2855 (that would needed `doctest-remote-data` to work along with `plot`)

Start by reviewing the documentation PNGs mentioned in the issue, then read #2855 and pytest-doctestplus issue #219 to understand the blocker around combining doctest-remote-data with the plot directive. Once that dependency supports the workflow, replace the applicable static figures with figures generated by the examples and verify the documentation build and doctests succeed.

Written by the indexing model from the issue text.