GS and physics small fixes

[CedricGuillemet]

Fixes for :

• https://forum.babylonjs.com/t/havok-plugin-dispose-returns-error/50087
• https://forum.babylonjs.com/t/gaussian-splatting-does-not-support-right-handed-system/50260
• https://forum.babylonjs.com/t/havok-incorrect-scaling-of-mesh-when-dragging-with-constraint/50113

[bjsplat]

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[bjsplat]

Snapshot stored with reference name:
refs/pull/15097/merge

Test environment:
https://babylonsnapshots.z22.web.core.windows.net/refs/pull/15097/merge/index.html

To test a playground add it to the URL, for example:

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WebGL2 visualization test reporter:

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/15097/merge/testResults/webgl2playwright/index.html

[bjsplat]

Visualization tests for WebGPU (Experimental)
Important - these might fail sporadically. This is an optional test.

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/15097/merge/testResults/webgpuplaywright/index.html