Fix sphinx-doc#9250: autodoc: The inherited method not having docstri…

…ng is wrongly parsed

`sphinx.util.inspect.getdoc()` clean the docstring up if the method is
inherited and not having docstring.  That causes indentations are
removed on processing it.

CHANGES

@@ -53,6 +53,7 @@ Bugs fixed
 * #8597: autodoc: a docsting having metadata only should be treated as
   undocumented
 * #9185: autodoc: typehints for overloaded functions and methods are inaccurate
+* #9250: autodoc: The inherited method not having docstring is wrongly parsed
 * #9217: manpage: The name of manpage directory that is generated by
   :confval:`man_make_section_directory` is not correct
 * #9224: ``:param:`` and ``:type:`` fields does not support a type containing