CLN: Clean-up use of super() in instance methods.
- [x] xref #25725

Simplifies the use of simple uses of ``super`` by converting to use python3 idioms. This is a quite big PR, but only deals with converting ``super(MyClass, self)`` to ``super()`` so it's very simple.

In addition to the uses of ``super`` dealt with in this PR, there are some more advanced uses of ``super`` in the code base, e.g. in classmethods and using ``super`` to jump to a specific point in the MRO-chain. I'd like to tackle those in a seperate PR in order to keep the the current large PR very simple.