Cap DROID wrist camera decalibration at the gripper

[alexmillane]

Summary

Bound DROID wrist camera decalibration

Detailed description

• The camera extrinsics variation drew offsets from a symmetric cube, so large +Y draws pushed the DROID wrist camera into the gripper body. Rendering 100 wrist frames across the sampled range showed the jaws intruding from about +0.01 m and the view substantially or fully occluded beyond +0.03 m.
• Added an overridable EmbodimentBase.get_camera_extrinsics_variation_cfg hook so an embodiment can seed per-camera decalibration bounds, and had DROID bound its wrist camera to [-0.06, -0.06, -0.06]..[0.06, 0.03, 0.06] in the ROS optical frame. The external cameras are unobstructed and keep the variation default.
• Dropped the duplicated wrist camera ranges from the robolab and camera sensitivity Experiments and from the OSMO benchmark submission script; they now inherit the embodiment bounds, and an explicit Experiment or Hydra override still takes precedence.
• Impact: any Experiment enabling this variation on DROID now gets 0.06 m of decalibration per axis instead of the 0.005 m default, capped at 0.03 m in +Y. Covered by a new case in test_camera_extrinsics_variation.py; the variations concept doc is updated to match.