review(ui-primitives): stop the size doc from enumerating native sizes

The parenthetical listed 14/16 and this branch added 20, but the set never
held to it: IconRightUpOutline14 defaults to 8, IconTreeCorner8x10 to 10,
and IconWarningOutline16 to 14. Drop the list rather than maintain one that
drifts, and retitle the icons test that carried the same generalization.

packages/client/ui-primitives/tests/icons.spec.tsx

@@ -36,7 +36,7 @@ describe('ic_ds_ icon set', () => {
     expect(svg.classList.contains('x')).toBe(true)
   })
 
-  it('native defaults: 14-glyphs default 14, 16-glyphs default 16, 20-glyphs default 20', () => {
+  it('each glyph defaults to its own drawn size, not one set-wide default', () => {
     const api = render(<IconApiOutline14 />)
     expect(api.container.querySelector('svg')!.getAttribute('width')).toBe('14')
     const folder = render(<IconFolderClose16 />)