[4.x] TypeVars rendered fullly qualified

Describe the bug

Trying Sphinx 4.0 (from master branch, commit c817c206265f545529b5fabe43fdf162bbc9bea2) I noticed that TypeVars are now rendered fully.qualified.T instead of just T like they used to in Sphinx 3.x.

To Reproduce

I'm using the following code in the example below (though with _E -> E, but that's not pertinent):

https://github.com/pytest-dev/pytest/blob/146eda93e7baf621475aef07be2c7b153f6acf03/src/_pytest/python_api.py#L577

Expected behavior

I think that for TypeVars specifically, for the vast majority of cases, it is better to only use the short name, even though it could cause an ambiguity.

Your project

https://github.com/pytest-dev/pytest

Screenshots

Before:

After:

Environment info

• OS: Linux
• Python version: 3.9.2
• Sphinx version: 4.0.0 (master branch) commit c817c206265f545529b5fabe43fdf162bbc9bea2
• Sphinx extensions:

extensions = [
    "pallets_sphinx_themes",
    "pygments_pytest",
    "sphinx.ext.autodoc",
    "sphinx.ext.autosummary",
    "sphinx.ext.intersphinx",
    "sphinx.ext.todo",
    "sphinx.ext.viewcode",
    "sphinx_removed_in",
    "sphinxcontrib_trio",
]

Reproduce the rendering change using the linked pytest example with Sphinx 4.x and compare it with Sphinx 3.x. Trace the autodoc or type-rendering entry point responsible for TypeVar names; done means TypeVars render as their short names rather than fully qualified names without regressing other type displays.