This commit adds 9 tests that check each of the default brush curve strength preset options to ensure that none of them cause NaN propagation. In total this takes approximately 0.7s to run to run. By design, these tests are very broad and are not a replacement for other testing, but they should help in reducing the chance of potential regressions. Related to #140162 Pull Request: https://projects.blender.org/blender/blender/pulls/140242