TSL: Revert positionWorld re-computation

[sunag]

Related issue: #32594 (comment), #32594 (comment)

Description

Revert the re-computation of positionWorld if .vertexNode is used.
This could be implemented in another PR with additional tests.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	355.36 84.47	355.36 84.47	+0 B +0 B
WebGPU	621.1 172.47	621.01 172.37	-97 B -98 B
WebGPU Nodes	619.71 172.23	619.61 172.13	-97 B -103 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	487.31 119.25	487.31 119.25	+0 B +0 B
WebGPU	692.34 187.8	691.86 187.76	-479 B -41 B
WebGPU Nodes	642.14 175.03	641.66 174.98	-479 B -50 B