fix splice hook

[sebavan]

https://forum.babylonjs.com/t/how-to-remove-node-in-rendertargettexture-renderlist/32375/5

[azure-pipelines]

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[azure-pipelines]

Snapshot stored with reference name:
refs/pull/12786/merge

Test environment:
https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12786/merge/index.html

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https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12786/merge/index.html#WGZLGJ#4600

Links to test babylon tools with this snapshot:

https://playground.babylonjs.com/?snapshot=refs/pull/12786/merge
https://sandbox.babylonjs.com/?snapshot=refs/pull/12786/merge
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https://playground.babylonjs.com/?snapshot=refs/pull/12786/merge#BCU1XR#0

[RaananW]

nitpicky - it is better to use oldSplice.call in that case. But the result is the same :-)