[`pydocstyle`] Handle arguments with the same names as sections (`D417`) (#16011)
## Summary
Fixes #16007. The logic from the last fix for this (#9427) was
sufficient, it just wasn't being applied because `Attributes` sections
aren't expected to have nested sections. I just deleted the outer
conditional, which should hopefully fix this for all section types.
## Test Plan
New regression test, plus the existing D417 tests.