Test failures when running on K8s pods or docker containers locally

I'm running `tests/scripts/run_tests.sh` with the `WEBFRAMEWORK=none` using the container `python:3.8`

```
=================================== FAILURES ===================================
_________________ test_file_is_readable_validator_not_readable _________________

tmpdir = local('/tmp/pytest-of-root/pytest-0/test_file_is_readable_validato2')

@pytest.mark.skipif(platform.system() == "Windows", reason="os.access() doesn't seem to work as we expect on Windows")
def test_file_is_readable_validator_not_readable(tmpdir):
p = tmpdir.join("nonreadable")
p.write("")
os.chmod(p.strpath, stat.S_IWRITE)
validator = FileIsReadableValidator()
with pytest.raises(ConfigurationError) as e:
> validator(p.strpath, "path")
E Failed: DID NOT RAISE

e =
p = local('/tmp/pytest-of-root/pytest-0/test_file_is_readable_validato2/nonreadable')
tmpdir = local('/tmp/pytest-of-root/pytest-0/test_file_is_readable_validato2')
validator =

tests/config/tests.py:287: Failed
=============================== warnings summary ===============================
tests/client/transaction_tests.py::test_transaction_span_stack_trace_min_duration_overrides_old_config
tests/client/transaction_tests.py::test_transaction_span_stack_trace_min_duration_overrides_old_config
tests/client/transaction_tests.py::test_transaction_span_stack_trace_min_duration_overrides_old_config
tests/client/transaction_tests.py::test_transaction_span_stack_trace_min_duration_overrides_old_config
/code/elasticapm/traces.py:909: DeprecationWarning: `span_frames_min_duration` is deprecated. Please use `span_stack_trace_min_duration`.
warnings.warn(

-- Docs: https://docs.pytest.org/en/stable/warnings.html
=========================== short test summary info ============================
FAILED tests/config/tests.py::test_file_is_readable_validator_not_readable - ...
============ 1 failed, 685 passed, 50 skipped, 4 warnings in 49.70s ============
make: *** [Makefile:14: test] Error 1
```

A similar error for other different python versions: `3.6`, `3.7`, `3.9` and `3.10`

You can reproduce the error with the below command that runs in one of the docker images I've created for testing [`skaffold`](https://github.com/elastic/apm-agent-python/pull/1659):

```bash
docker run --rm -ti docker.elastic.co/beats-dev/apm-agent-python-3_10:v6.12.0-19-gdf6fc75d-dirty@sha256:ad548ceef42ed963c373b0b28ab3b3d33ac016e886fe82d2fce5d8443f753783 /bin/bash -c "WEBFRAMEWORK=none tests/scripts/run_tests.sh"
```

The docker image content:

```Dockerfile
ARG VERSION
FROM python:${VERSION}
WORKDIR /code
ADD . .
ENV WEBFRAMEWORK=none
```

tests/config/tests.py と test_file_is_readable_validator_not_readable から始め、報告されている Python Docker images で WEBFRAMEWORK=none を指定して tests/scripts/run_tests.sh を通じて再現します。コンテナの権限下でのバリデーターの動作を比較します。影響を受ける Docker および Kubernetes 環境でテストスイートが成功し、想定される読み取り不可ファイルのチェックを壊していなければ完了です。

索引モデルが issue の本文から書いたものです。