WebGPURenderer: remove useless call in WebGL fallback

[aardgoose]

Related issue: #29622

The call to createBindings() call doesn't do anything, bindings are already created at this point.
Remove call and also the now pointless check for this null.

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	689.92 170.93	689.92 170.93	+0 B +0 B
WebGPU	814.86 219.4	814.81 219.39	-47 B -17 B
WebGPU Nodes	814.36 219.27	814.32 219.25	-47 B -17 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	462.94 111.81	462.94 111.81	+0 B +0 B
WebGPU	537.67 145.07	537.62 145.06	-47 B -17 B
WebGPU Nodes	493.78 134.81	493.74 134.79	-47 B -17 B