ENH: Make `deprecate_nonkeyword_arguments` alter function signature

[hauntsaninja]

Feature Type

• Adding new functionality to pandas

• Changing existing functionality in pandas

• Removing existing functionality in pandas

Problem Description

Currently deprecate_nonkeyword_arguments does not alter the function signature. This means that help and ?? will show the deprecated signatures. This also affects recent attempts to achieve better typing of pandas using stubtest, e.g. see #47817 (review) and python/mypy#13703

Feature Description

Set the __signature__ attr on the decorated function

Alternative Solutions

Wait for all the removals to take place

Additional Context

No response

[hauntsaninja]

Opened PR at #48693 cc @twoertwein