New versions of sphinx starting showing `__init__` parameters even when
we don't want them to show because they are private (have `_ispytest`
argument).
The only working solution I found was to switch to
`autodoc_typehints_description_target = "documented"` and explicitly
document parameters for which we want to show the types. It's a little
tedious and repetitive in some simple cases, but overall it results in
nicer API docs.
7431750bb6