Reinitialize holonomic robot setup when prim paths change

[sylvesterkaczmarek]

Description

Make HolonomicRobotUsdSetup refresh its cached robot parameters when robotPrim or comPrim is retargeted.

The node already detects path changes and updates the stored strings, but it leaves state.initialized set and retains the previous HolonomicRobotUsdSetup object. The existing initialization guard then skips rebuilding the setup and the node continues publishing wheel parameters from the old robot.

Clear the cached parameter object and mark the state uninitialized whenever either prim path changes. The normal initialization path then rebuilds parameters for the new target.

Validation

• focused regression test computes once for Robot A
• changes robot and COM paths to Robot B
• verifies HolonomicRobotUsdSetup is constructed for both targets
• verifies outputs switch to Robot B wheel parameters
• production change is two lines