GPUPicker: Fix multiPickAsync return unexpected results in different hardwareScalingLevel

[KallkaGo]

see https://forum.babylonjs.com/t/gpu-multi-picking-issues/58074/2 and https://forum.babylonjs.com/t/gpu-picker-multi-pick-adjust-to-dpr/58091

In multiPickAsync, when the length of the screen coordinate array passed in is greater than 1, it is not processed to adapt to the current DPR, resulting in unexpected results being returned.

[bjsplat]

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[bjsplat]

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