FIX: Remove xlink:href to favour href due to deprecation (PR #14854)

Based on docs here <use> - SVG: Scalable Vector Graphics | MDN, the xlink:href attribute is deprecated and we should probably move away from it soon. Can also confirm that the removal of xlink made the feature work.

(No test updates, since our method of testing uses attributes, and testing for the attribute doesn’t necessitate the visibility of the svg. Whereas snapshot testing may cover absence of the rendered icon)