.wikitable specificity was increased due to T32485: Hieroglyphs look scary if embedded in tables with class="wikitable" and T35434: math extension: integral expressions display with boxes/frames/borders, but I couldn't find need of table.wikitable in current testing of pages described back then. The direct child selectors > seem sufficient on their own.
Let's remove table part as
- it makes styling overrides unnecessary more complex
- overqualifying selector by HTML element is seen as bad practices (class could be reused with other elements)
- it is nowhere used apart form a table element in known projects to us
- adds extra bytes sent to client