WebGPUBackend: Revert onSubmittedWorkDone usage in timestamp queries

[RenaudRohlinger]

Related issue: #29970

Description

Partially revert #29970 as the usage of await this.device.queue.onSubmittedWorkDone(); seems too heavy on the CPU (add an average of 3ms) and should be manually handled by the developer using renderer.waitForGPU() if needed instead.

This contribution is funded by Utsubo

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	339.11 78.98	339.11 78.98	+0 B +0 B
WebGPU	484.81 134.59	484.77 134.58	-46 B -3 B
WebGPU Nodes	484.28 134.49	484.23 134.49	-46 B -3 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	465 112.04	465 112.04	+0 B +0 B
WebGPU	554.15 150.01	554.1 150	-46 B -4 B
WebGPU Nodes	510.03 139.72	509.98 139.72	-46 B -4 B