Move raw multimodal Tensors to CUDA before inference request checkpoint recomp.

[cspades]

• I, the PR author, have personally reviewed every line of this PR.

What does this PR do?

• Made a mistake while addressing this comment to clear out the multimodal embedding cache during engine pause where I added the recomp through the vision encoder but did not move the image tensor inputs to CUDA.
  • Mirrors what _build_vlm_request does, moving all the image tensors to CUDA before the encoder forward pass.
  • Unfortunately, since I didn't write a unit test for this feature and RL dictates whether we use this path, this bug elluded me.

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