Exporter creates animation tracks even for non-animated vertex groups

It appears the collada exporter is inserting originally-non-existing keyframes and tracks for vertex group which don't appear in the action at all. I initially thought Godot was responsible for this but in
[this issue](https://github.com/godotengine/godot/issues/6595), I believe reduz is saying that it is collada-exporter that is creating such keyframes, and nothing can be done on Godot side after the collada file created.