Tweak sphere rew

[Yasu31]

Note: merge only after I fix the todo in #4
The implementation of the sphere rotation reward had a “bug” in it… it’s a different shape based on the direction of rotation, when the direction is -1 it doesn’t decrease when the velocity magnitude is larger than 2 rad/s

Maybe that is why the -1 direction trained much better, thanks to this unintended bug, I’m retraining +1 direction with the same reward profile to see if it’s better

This reward seems to work more consistently and use each finger equally for the +1 direction, than for the original reward (for the -1 direction, the implementation remains exactly the same

checklist

PR can be merged after all these are met

• describe the changes (with screenshots if it helps)
• If this PR modifies any part of the training, post the W&B results of the following experiments (post screenshot of the consecutive_successes)

  python train.py task=FaiveHandP0 capture_video=True force_render=False wandb_activate=True wandb_group=srl_ethz wandb_project=faive_hand wandb_name=faivehandp0_check

• compare with multiple random seeds if this is actually better