1.1.1: pytest is failing when `pytest-randomly` is used

## System Info

- 🖥 **OS name and version**: Linux/x86_64
- 🐍 **Python version**: 3.8.12
- 🏹 **Arrow version**: 1.1.1

Looks like pytest is failing when `pytest-randomly` is installed.
Example:
```console
+ PYTHONPATH=/home/tkloczko/rpmbuild/BUILDROOT/python-arrow-1.1.1-2.1.fc35.x86_64/usr/lib64/python3.8/site-packages:/home/tkloczko/rpmbuild/BUILDROOT/python-arrow-1.1.1-2.1.fc35.x86_64/usr/lib/python3.8/site-packages
+ /usr/bin/pytest -ra -q
=========================================================================== test session starts ============================================================================
platform linux -- Python 3.8.12, pytest-6.2.5, py-1.10.0, pluggy-0.13.1
benchmark: 3.4.1 (defaults: timer=time.perf_counter disable_gc=False min_rounds=5 min_time=0.000005 max_time=1.0 calibration_precision=10 warmup=False warmup_iterations=100000)
Using --randomly-seed=457307952
rootdir: /home/tkloczko/rpmbuild/BUILD/arrow-1.1.1, configfile: tox.ini, testpaths: tests
plugins: forked-1.3.0, shutil-1.7.0, virtualenv-1.7.0, expect-1.1.0, flake8-1.0.7, timeout-1.4.2, betamax-0.8.1, freezegun-0.4.2, aspectlib-1.5.2, toolbox-0.5, rerunfailures-9.1.1, requests-mock-1.9.3, cov-2.12.1, flaky-3.7.0, benchmark-3.4.1, xdist-2.3.0, pylama-7.7.1, datadir-1.3.1, regressions-2.2.0, cases-3.6.3, xprocess-0.18.1, black-0.3.12, anyio-3.3.0, asyncio-0.15.1, trio-0.7.0, subtests-0.5.0, isort-2.0.0, hypothesis-6.14.6, mock-3.6.1, profiling-1.7.0, randomly-3.8.0, Faker-8.12.1, nose2pytest-1.0.8, pyfakefs-4.5.1, tornado-0.8.1, twisted-1.13.3
collected 1737 items

tests/test_factory.py ................................................ [ 2%]
tests/test_util.py ..... [ 3%]
tests/test_formatter.py ............................................................................................................................................ [ 11%]
.................................................................................................................................................................... [ 20%]
.................................................................................................................................................................... [ 29%]
....................................................................................................................................................... [ 38%]
tests/test_arrow.py ............X..............x.................................................................................................................... [ 46%]
.................................................................... [ 50%]
tests/test_api.py .... [ 51%]
tests/test_parser.py ............................................................................................................................................... [ 59%]
.................................................................................................................................................................... [ 68%]
.................................................................................................................................................................... [ 78%]
.................................................................................................................................................................... [ 87%]
.................................................................................. [ 92%]
tests/test_locales.py ...................................................................................................FF............................... [100%]

================================================================================= FAILURES =================================================================================
_____________________________________________________________ TestLocaleValidation.test_locale_name_validation _____________________________________________________________

self =

def test_locale_name_validation(self):

for locale_cls in self.locales.values():
for locale_name in locale_cls.names:
> assert len(locale_name) == 2 or len(locale_name) == 5
E AssertionError: assert (3 == 2 or 3 == 5)
E + where 3 = len('foo')
E + and 3 = len('foo')

tests/test_locales.py:40: AssertionError
_______________________________________________________________ TestLocaleValidation.test_locale_validation ________________________________________________________________

self =

def test_locale_validation(self):

for locale_cls in self.locales.values():
# 7 days + 1 spacer to allow for 1-indexing of months
> assert len(locale_cls.day_names) == 8
E AssertionError: assert 0 == 8
E + where 0 = len([])
E + where [] = .CustomLocale1'>.day_names

tests/test_locales.py:14: AssertionError
============================================================================= warnings summary =============================================================================
../../../../../usr/lib/python3.8/site-packages/dateutil/zoneinfo/__init__.py:26
/usr/lib/python3.8/site-packages/dateutil/zoneinfo/__init__.py:26: UserWarning: I/O error(2): No such file or directory
warnings.warn("I/O error({0}): {1}".format(e.errno, e.strerror))

-- Docs: https://docs.pytest.org/en/stable/warnings.html

---------- coverage: platform linux, python 3.8.12-final-0 -----------
Name Stmts Miss Branch BrPart Cover Missing
----------------------------------------------------------------
arrow/__init__.py 7 0 0 0 100%
arrow/_version.py 1 0 0 0 100%
arrow/api.py 30 0 0 0 100%
arrow/arrow.py 550 0 239 0 100%
arrow/constants.py 11 0 0 0 100%
arrow/factory.py 86 0 48 0 100%
arrow/formatter.py 102 0 72 0 100%
arrow/locales.py 965 0 144 0 100%
arrow/parser.py 313 0 142 0 100%
arrow/util.py 45 0 22 0 100%
----------------------------------------------------------------
TOTAL 2110 0 667 0 100%
Coverage XML written to file coverage.xml

Required test coverage of 99% reached. Total coverage: 100.00%
========================================================================= short test summary info ==========================================================================
XFAIL tests/test_arrow.py::TestArrowHumanize::test_month
known issue with humanize month limits
XPASS tests/test_arrow.py::TestArrowHumanize::test_months known issue with humanize month limits
FAILED tests/test_locales.py::TestLocaleValidation::test_locale_name_validation - AssertionError: assert (3 == 2 or 3 == 5)
FAILED tests/test_locales.py::TestLocaleValidation::test_locale_validation - AssertionError: assert 0 == 8
===================================================== 2 failed, 1733 passed, 1 xfailed, 1 xpassed, 1 warning in 14.78s =====================================================
pytest-xprocess reminder::Be sure to terminate the started process by running 'pytest --xkill' if you have not explicitly done so in your fixture with 'xprocess.getinfo().terminate()'.
```
As long as randomly plugin is disaled everything is fine:
```console
+ PYTHONPATH=/home/tkloczko/rpmbuild/BUILDROOT/python-arrow-1.1.1-2.1.fc35.x86_64/usr/lib64/python3.8/site-packages:/home/tkloczko/rpmbuild/BUILDROOT/python-arrow-1.1.1-2.1.fc35.x86_64/usr/lib/python3.8/site-packages
+ /usr/bin/pytest -ra -q -p no:randomly
=========================================================================== test session starts ============================================================================
platform linux -- Python 3.8.12, pytest-6.2.5, py-1.10.0, pluggy-0.13.1
benchmark: 3.4.1 (defaults: timer=time.perf_counter disable_gc=False min_rounds=5 min_time=0.000005 max_time=1.0 calibration_precision=10 warmup=False warmup_iterations=100000)
rootdir: /home/tkloczko/rpmbuild/BUILD/arrow-1.1.1, configfile: tox.ini, testpaths: tests
plugins: forked-1.3.0, shutil-1.7.0, virtualenv-1.7.0, expect-1.1.0, flake8-1.0.7, timeout-1.4.2, betamax-0.8.1, freezegun-0.4.2, aspectlib-1.5.2, toolbox-0.5, rerunfailures-9.1.1, requests-mock-1.9.3, cov-2.12.1, flaky-3.7.0, benchmark-3.4.1, xdist-2.3.0, pylama-7.7.1, datadir-1.3.1, regressions-2.2.0, cases-3.6.3, xprocess-0.18.1, black-0.3.12, anyio-3.3.0, asyncio-0.15.1, trio-0.7.0, subtests-0.5.0, isort-2.0.0, hypothesis-6.14.6, mock-3.6.1, profiling-1.7.0, Faker-8.12.1, nose2pytest-1.0.8, pyfakefs-4.5.1, tornado-0.8.1, twisted-1.13.3
collected 1737 items

tests/test_api.py .... [ 0%]
tests/test_arrow.py ................................................................................................................................................ [ 8%]
....................x.X............................................. [ 12%]
tests/test_factory.py ................................................ [ 15%]
tests/test_formatter.py ............................................................................................................................................ [ 23%]
.................................................................................................................................................................... [ 32%]
.................................................................................................................................................................... [ 42%]
....................................................................................................................................................... [ 50%]
tests/test_locales.py .................................................................................................................................... [ 58%]
tests/test_parser.py ............................................................................................................................................... [ 66%]
.................................................................................................................................................................... [ 76%]
.................................................................................................................................................................... [ 85%]
.................................................................................................................................................................... [ 94%]
.................................................................................. [ 99%]
tests/test_util.py ..... [100%]

============================================================================= warnings summary =============================================================================
../../../../../usr/lib/python3.8/site-packages/dateutil/zoneinfo/__init__.py:26
/usr/lib/python3.8/site-packages/dateutil/zoneinfo/__init__.py:26: UserWarning: I/O error(2): No such file or directory
warnings.warn("I/O error({0}): {1}".format(e.errno, e.strerror))

-- Docs: https://docs.pytest.org/en/stable/warnings.html

---------- coverage: platform linux, python 3.8.12-final-0 -----------
Name Stmts Miss Branch BrPart Cover Missing
----------------------------------------------------------------
arrow/__init__.py 7 0 0 0 100%
arrow/_version.py 1 0 0 0 100%
arrow/api.py 30 0 0 0 100%
arrow/arrow.py 550 0 239 0 100%
arrow/constants.py 11 0 0 0 100%
arrow/factory.py 86 0 48 0 100%
arrow/formatter.py 102 0 72 0 100%
arrow/locales.py 965 0 144 0 100%
arrow/parser.py 313 0 142 0 100%
arrow/util.py 45 0 22 0 100%
----------------------------------------------------------------
TOTAL 2110 0 667 0 100%
Coverage XML written to file coverage.xml

Required test coverage of 99% reached. Total coverage: 100.00%
========================================================================= short test summary info ==========================================================================
XFAIL tests/test_arrow.py::TestArrowHumanize::test_month
known issue with humanize month limits
XPASS tests/test_arrow.py::TestArrowHumanize::test_months known issue with humanize month limits
========================================================== 1735 passed, 1 xfailed, 1 xpassed, 1 warning in 12.92s ==========================================================
pytest-xprocess reminder::Be sure to terminate the started process by running 'pytest --xkill' if you have not explicitly done so in your fixture with 'xprocess.getinfo().terminate()'.
```
To diagnose that kind of issues https://github.com/mrbean-bremen/pytest-find-dependencies/ can be used.

Start by running the commands shown with and without pytest-randomly, then inspect tests/test_locales.py and the failing TestLocaleValidation tests. Reproduce the order-dependent failure and trace how the custom locale tests affect validation; done means the full suite passes with pytest-randomly enabled as well as disabled.

Written by the indexing model from the issue text.