PMREMNode: Fix dispose of internal PMREMs.

[Mugen87]

Fixed #33846.

Description

The PR makes sure PMREMNode removes the internal PMRME if a its source texture is disposed of.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	365.63 86.86	365.63 86.86	+0 B +0 B
WebGPU	666.94 184.9	667.1 184.95	+154 B +44 B
WebGPU Nodes	664.99 184.59	665.14 184.64	+154 B +44 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	507.76 123.44	507.76 123.44	+0 B +0 B
WebGPU	746.61 201.33	746.77 201.38	+154 B +48 B
WebGPU Nodes	696.96 188.93	697.11 188.96	+154 B +36 B