Remove duplicated statistics tests in parquet (apache#6190)

* move all tests to parquet/tests/arrow_reader/statistics.rs, and leave a comment in original file

* remove duplicated tests and adjust the empty tests

* data file tests brought folders changes

* fix lint

* add comments

Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

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Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>