Blender Git Loki

Cleanup: Avoid setting (unsafe) Outliner tree element data that won't be used

I carefully checked and am quite sure for `TSE_ANIMATION_DATA` and
`TSE_NLA_ACTION` the direct-data isn't used at all. This data is stored and
accessed in unsafe ways based on conventions anyway (`void *`). We should aim
for a safer design but it will be difficult to get there. Any removed
complexity will help.