Clean up a keyframe insertion unit test I just committed, as it had some commented-out code that shouldn't have been commented out. The test logic could also be simplified, as the complexity was necessary for replaying the broken test case, but not necessary for testing the actual underlying behaviour. No functional changes. Ref: 2dba943341ce7a7706c3865b4b7b1cfc5d6bb746 Pull Request: https://projects.blender.org/blender/blender/pulls/128379