icons: remove design from codeowners and optimize icons (#98633)

The icons have excessive precision. Removing design from ownership of
icons as we need to manage UI2 - each icons needs a stroke and path
counterpart, so we can't just swap these freely

Author: JonasBa

.github/CODEOWNERS

@@ -125,7 +125,6 @@ package.json                                             @getsentry/owners-js-de
 pnpm-lock.yaml                                           @getsentry/owners-js-deps
 
 ## Design
-/static/app/icons/                                       @getsentry/design
 /static/fonts/                                           @getsentry/design
 /static/images/                                          @getsentry/design