autodoc pulls parent constructor docstring when subclass has its own constructor

Describe the bug
When a sub-class defines an override for init, if a docstring isn't provided autodoc pulls the docstring from the parent class constructor. This doesn't make sense since the override can present a different set of arguments.

I'm guessing this behavior matches how function docstrings are inherited. For functions this behavior makes sense because, I think, modifying the function parameters on an override would violate the Liskov substitution principle. I don't think constructors are expected to comply with LSP as the idea is that a constructed subclass instance may by substituted for the base but how it is constructed may be changed.

To Reproduce
The following is an example class

class BaseClassHasInitDocString:
    """
    This base class properly documents ``__init__``
    """
    def __init__(self, param1: int, param2: str):
        """
        My constructor documentation

        :param param1: my int param
        :param param2:  my string param
        """

class SubClassOverridesButNoDocString(BaseClassHasInitDocString):
    """
    This sub-class overrides the constructor with different parameters but fails to provide a docstring.

    Parent constructor's docstring shouldn't be inherited here because an override exists
    """
    def __init__(self, param: bool):
        super(SubClassOverridesButNoDocString, self).__init__(5, "default string")

class SubClassHasNoConstructor(BaseClassHasInitDocString):
    """
    This sub-class doesn't override constructor.  Constructor documentation correctly matches parent class constructor
    """

The following options are in conf.py

# Custom theme from ReadTheDocs
html_theme = 'alabaster'

# options for autodoc
autodoc_default_options = {
    'member-order': 'bysource',
    'members': True,
    'undoc-members': True,
    'show-inheritance': True,
}
autodoc_typehints = 'signature'
autoclass_content = 'both'

This is the simple index.rst

Hello World
===========

code docs
=========

.. automodule:: helloworld.helloworld

Expected behavior
If constructor is overridden, docstring should match the overridden constructor even if it isn't explicitly provided.

Your project
Example provided above.

Screenshots

Environment info

• OS: Ubuntu 20.04
• Python version: 3.8.2
• Sphinx version: 3.2.1
• Sphinx extensions: sphinx.ext.autodoc
• Extra tools:

Additional context
Add any other context about the problem here.

• [e.g. URL or Ticket]

Reproduce the behavior using the classes, conf.py, and index.rst example with the sphinx.ext.autodoc extension. Start by tracing how autodoc handles inherited constructor docstrings, then verify that an overridden constructor does not receive the parent docstring while a subclass without its own constructor still does.