TST/CLN: Remove unnecessary pyarrow version checking
I think this shouldn't be necessary since 7.0 is the minimum version supported now.

FAILED pandas/tests/indexes/test_common.py::test_sort_values_invalid_na_position[string-pyarrow-None] - AssertionError: Did not see expected warning of class 'PerformanceWarning'
FAILED pandas/tests/indexes/test_common.py::test_sort_values_invalid_na_position[string-pyarrow-middle] - AssertionError: Did not see expected warning of class 'PerformanceWarning'
 Looks like the (some?) failures are due to https://github.com/pandas-dev/pandas/pull/51483 (should have been more careful with merging after being stricter with the warnings) Can you remove my tm.assert_produces_warning when you are ready here? > Can you remove my tm.assert_produces_warning when you are ready here?

Sure, done in the last commit.

Going to merge and backport just in case 2.0 has any PRs that impact `test_arrow.py`