[Python][Parquet] Reorganize Parquet reader docstrings

### Describe the enhancement requested

In the Python Parquet reader docstrings, many snippets are duplicated for describing various common options, such as `thrift_string_size_limit`.

We should deduplicate these snippets and find a way to reuse them across all Parquet reader docstrings. This will ease maintenance and reduce the risk of errors when updating those docstrings.

### Component(s)

Parquet, Python

Locate the Python Parquet reader docstrings and compare the repeated option snippets, starting with the thrift_string_size_limit text named in the issue. Identify a reusable way to share those snippets across the reader docstrings; done means duplicated wording is removed while the documented options remain complete and consistent.

Written by the indexing model from the issue text.