Remove teleoperation models for icub2.5 and icub3

The objective is to get rid of the teleoperation models found in https://github.com/robotology/human-dynamics-estimation/tree/master/conf/urdfs which are copies of the original robot urdf files (contained in https://github.com/robotology/icub-models) with the addition of fake links originally added to replicate the orientation of the sensors data.

Those links added to the urdfs are no longer necessary after https://github.com/robotology/human-dynamics-estimation/pull/254.

In fact, for example, the `ergoCub` model was added and tested (https://github.com/robotology/human-dynamics-estimation/pull/340) by using directly the original model by adding all the required fixed transforms to the configuration file (see https://github.com/robotology/human-dynamics-estimation/blob/11ad67f1d31f54d42aa1954a6a1a6e83a5892570/conf/xml/RobotStateProvider_ergoCub_openxr_ifeel.xml#L104-L137). Since the `ergoCub` model should basically have same (or similar) link definition as the `iCub3` (and `iCub2.5`) models, starting from those transforms we should be able to get rid of the teleoperation models.

cc @mebbaid @S-Dafarra