Make the RNA property `prefs.experimental.use_animation_baklava` read-only
when Blender was built without experimental features.
This reverts parts of b46e2e6300, which
completely removed the flag. That was a bit over-zealous, as there is still
Python code that checks it. Now it always stays `False` on non-experimental
builds.
Pull Request: https://projects.blender.org/blender/blender/pulls/128494