fix(cdk/scrolling): virtual-scroll flickers in zoneless mode

[OonihiloO]

When provideExperimentalZonelessChangeDetection is enabled,
virtual-scroll-viewport flickers during scroll because the transform operation becomes visible.
This fix uses AfterRenderPhase to ensure this operation stays invisible,
despite provideExperimentalZonelessChangeDetection being used or not.

Fixes #29174

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