ergoCub SN001/ ergoCubGazeboV1_1*: the waist imu is still added as xml blob to the urdf

[Nicogene]

Task description

This is not a problem, but I noticed that the waist imu is added as xml blob, because when we didn't have creo2urdf we made some workarounds:

• Workarounds, limitations/missing features in ergocub 1.0 urdf #106

https://github.com/icub-tech-iit/ergocub-software/blob/d6eba9975e1c3be1201c9118e392130763459739/urdf/creo2urdf/data/ergocub1_1/ERGOCUB_all_options.yaml#L1054-L1085

But I don't see the waist imu csys in the simulation model cad.

Definition of Done

We export the waist imu as sensor not as xmlBlob

cc @Mick3Lozzo @pattacini