PostProcessingUtils: Improve names, replaced some save to reset

[sunag]

Related issue: #29595 (comment)

Description

Improve names, replaced some save to reset

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	689.82 170.9	689.82 170.9	+0 B +0 B
WebGPU	811.49 218.59	811.5 218.59	+10 B +5 B
WebGPU Nodes	811 218.46	811.01 218.47	+10 B +5 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	462.84 111.78	462.84 111.78	+0 B +0 B
WebGPU	535.71 144.58	535.71 144.58	+0 B +0 B
WebGPU Nodes	491.83 134.32	491.83 134.32	+0 B +0 B

[Mugen87]

We now might want to honor SSRNode in this PR^^.