fix(GlSkeletonLoader): Disable animation for prefers-reduced-motion

What does this MR do?

Don't animation skeleton loader when Reduce motion accessibility preference is enabled.

View demo

Skeleton loader not being animated while Reduced Motion is enabled. Then setting is disabled, page is refreshed, and the animation returns

Does this MR meet the acceptance criteria?

Conformity

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• GitLab UI's contributing guidlines.
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• Added the ~"component:*" label(s) if applicable.

Closes #1876 (closed)