[Task]: Update Python slowly updating side input example

What needs to happen?

https://beam.apache.org/documentation/patterns/side-inputs/ is missing a side input pattern for Python

When doing this, we should factor in https://github.com/apache/beam/issues/35934 (and probably use Latest.Globally.without_defaults() and test on Dataflow)

Issue Priority

Priority: 2 (default / most normal work should be filed as P2)

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