les: remove obsolete code related to PoW header syncing (#27737)

This change removes PoW header syncing related code from LES and also deletes 
duplicated packages les/catalyst, les/downloader and les/fetcher. These package copies
were created because people wanted to make changes in their eth/ counterparts, but weren't
able to adapt LES code to the API changes.

cmd/geth/main.go

@@ -93,9 +93,6 @@ var (
 		utils.LightMaxPeersFlag,
 		utils.LightNoPruneFlag,
 		utils.LightKDFFlag,
-		utils.UltraLightServersFlag,
-		utils.UltraLightFractionFlag,
-		utils.UltraLightOnlyAnnounceFlag,
 		utils.LightNoSyncServeFlag,
 		utils.EthRequiredBlocksFlag,
 		utils.LegacyWhitelistFlag,