doc/flaky: remove box/flaky plugin suggestion (pytest-dev#12100)

The plugin is abandoned and no longer working with new pytest versions.

I also reordered a bit to put pytest-rerunfailures first since it seems most maintained and is under pytest-dev.

doc/en/explanation/flaky.rst

@@ -52,10 +52,9 @@ Plugins
 
 Rerunning any failed tests can mitigate the negative effects of flaky tests by giving them additional chances to pass, so that the overall build does not fail. Several pytest plugins support this:
 
-* `flaky <https://github.com/box/flaky>`_
-* `pytest-flakefinder <https://github.com/dropbox/pytest-flakefinder>`_ - `blog post <https://blogs.dropbox.com/tech/2016/03/open-sourcing-pytest-tools/>`_
 * `pytest-rerunfailures <https://github.com/pytest-dev/pytest-rerunfailures>`_
 * `pytest-replay <https://github.com/ESSS/pytest-replay>`_: This plugin helps to reproduce locally crashes or flaky tests observed during CI runs.
+* `pytest-flakefinder <https://github.com/dropbox/pytest-flakefinder>`_ - `blog post <https://blogs.dropbox.com/tech/2016/03/open-sourcing-pytest-tools/>`_
 
 Plugins to deliberately randomize tests can help expose tests with state problems: