`tests/test_grdwindinversion_ci.py` is too long to be a unit test

[agrouaze]

Currently tests/test_grdwindinversion_ci.py::test_makeL2_generation last for 11 min ;:

======== 1 passed, 6 warnings in 660.12s (0:11:00) ========

We need to replace this test by smaller tests.

and move tests/test_grdwindinversion_ci.py to another repository highlevel-tests for instance.