Disable the "views_test_data" module in tests

The views_test_data, on which our search_api_test_views module depends, can interfere with some tests. Most notably, it causes the Search API Saved Searches module to fail tests against Drupal 10.3 (though it’s still unclear what changed in that specific version). Since I don’t think we actually need that module in our tests, I think we can just remove it.