🗑️(convert) cleanup old content route

Remove rout /api/content, there is no more controller behind and is not
used anymore.

src/frontend/servers/y-provider/src/routes.ts

@@ -2,6 +2,5 @@ export const routes = {
   COLLABORATION_WS: '/collaboration/ws/',
   COLLABORATION_RESET_CONNECTIONS: '/collaboration/api/reset-connections/',
   CONVERT: '/api/convert/',
-  CONTENT: '/api/content/',
   COLLABORATION_GET_CONNECTIONS: '/collaboration/api/get-connections/',
 };