Fix leaky tests part 2 : AWS Settings overrides

In arkindex.images.tests, multiple modules override some AWS related methods. In this test_image, some AWS settings are overriden on the class level. That causes some leakage on other tests.

To fix this, we override the needed settings on each test case.

requested review from @erwanrouchet

assigned to @schneider-y

approved this merge request

mentioned in commit 0509fa55

merged

mentioned in issue #1005 (closed)