geometry: skip getFloatData if not needed (#17031)

The `setVerticesBuffer` method currently unconditionally calls
`buffer.getFloatData` when setting a position buffer. However, if
`useBoundingInfoFromGeometry` is true and `_boundingInfo` is already set
(a common scenario for glTF models), the data returned by `getFloatData`
is ignored within the `_updateExtend` method.

This `getFloatData` operation is profiled to be CPU and RAM intensive,
contributing significantly to model loading times and potentially
causing major garbage collection events.

This change optimizes performance by conditionally calling
`buffer.getFloatData`. It now passes `null` to `_updateExtend` when
`useBoundingInfoFromGeometry` is true and `_boundingInfo` exists,
ensuring the expensive data retrieval is only performed when its result
is actually needed and used. This will improve loading performance and
reduce GC pressure, particularly for glTF assets.

Forum post:
<https://forum.babylonjs.com/t/redundant-getfloatdata-in-geometry-setverticesbuffer/60063>

Author: kzhsw

packages/dev/core/src/Meshes/geometry.ts

@@ -310,7 +310,7 @@ export class Geometry implements IGetSetVerticesData {
         if (kind === VertexBuffer.PositionKind) {
             this._totalVertices = totalVertices ?? buffer._maxVerticesCount;
 
-            this._updateExtend(buffer.getFloatData(this._totalVertices));
+            this._updateExtend(this.useBoundingInfoFromGeometry && this._boundingInfo ? null : buffer.getFloatData(this._totalVertices));
             this._resetPointsArrayCache();
 
             // this._extend can be empty if buffer.getFloatData(this._totalVertices) returned null