Case C-128/19: Judgment of the Court (Fourth Chamber) of 20 May 2021 (request for a preliminary ruling from the Corte suprema di cassazione — Italy) — Azienda Sanitaria Provinciale di Catania v Assessorato della Salute della Regione Siciliana (Reference for a preliminary ruling — State aid — Agriculture sector — Slaughtering of animals affected by infectious diseases — Compensation for farmers — Notification and standstill requirements — Article 108(3) TFEU — Concepts of ‘existing aid’ and ‘new aid’ — Regulation (EC) No 659/1999 — Exemptions by categories of aid — Regulation (EU) No 702/2014 — De minimis aid — Regulation (EU) No 1408/2013)