ImportPathMismatchError after recent nextland integration test tweaks

[soxofaan]

Integration tests started to fail with weird error

ImportError while loading conftest '/var/lib/jenkins/workspace/openEO/openeo-integrationtests/nextland/tests/conftest.py'.
_pytest.pathlib.ImportPathMismatchError: ('tests.conftest', '/var/lib/jenkins/workspace/openEO/openeo-integrationtests/openeo-geopyspark-integrationtests/tests/conftest.py', PosixPath('/var/lib/jenkins/workspace/openEO/openeo-integrationtests/nextland/tests/conftest.py'))

[soxofaan]

Caused by recent changes in nextland repo related to #8 and #6

now both openeo-geopyspark-integrationtests and nextland have this in their tree structure:

└── tests
    ├── conftest.py
    ├── __init__.py

and the module reference tests.conftest is now ambiguous for the conftest discovery mechanism: see pytest-dev/pytest#11206

[soxofaan]

for now fixed by eliminating some __init__.py files from nextland test file structure