CLN/TST: Remove testing ArrowExtensionArray in favor of `extensions/test_arrow.py`
closes https://github.com/pandas-dev/pandas/issues/46008


1. `extension/arrow/test_timestamp.py`: The original issue https://github.com/pandas-dev/pandas/issues/34986 (ExtensionDtypes with kind="M") is more-narrowly tested in https://github.com/pandas-dev/pandas/pull/48640 and the DataFrame construction is tested in `pandas/tests/extension/test_arrow.py::TestConstructors` as `ArrowDtype(pa.timestamp())` has kind="M"

2. `extension/arrow/test_string.py`: Moved test to `pandas/tests/extension/test_string.py`

3. `extension/arrow/test_bool.py`: Moved `test_is_bool_dtype` and `test_basic_equals` to `extensions/test_arrow.py` The rest of the test appeared to be a subset of what is tested in `test_arrow.py`


thx @mroeschke 