when a <TH> has class no-sort, and the a11y addon is used, the table header cell still has A11Y attributes applied. Specifically tab-index="0" and aria-label="...".
Expected behaviour:
When class no-sort is applied to the <TH> element, the tab-index would be removed or set to -1, and the aria-label will be removed or set to "" (or have a string such as colum foo cannot be sorted).