all: remove the Rinkeby testnet (#27406)

cmd/geth/main.go

@@ -259,9 +259,6 @@ func main() {
 func prepare(ctx *cli.Context) {
 	// If we're running a known preset, log it for convenience.
 	switch {
-	case ctx.IsSet(utils.RinkebyFlag.Name):
-		log.Info("Starting Geth on Rinkeby testnet...")
-
 	case ctx.IsSet(utils.GoerliFlag.Name):
 		log.Info("Starting Geth on Görli testnet...")
 
@@ -293,7 +290,6 @@ func prepare(ctx *cli.Context) {
 	if ctx.String(utils.SyncModeFlag.Name) != "light" && !ctx.IsSet(utils.CacheFlag.Name) && !ctx.IsSet(utils.NetworkIdFlag.Name) {
 		// Make sure we're not on any supported preconfigured testnet either
 		if !ctx.IsSet(utils.SepoliaFlag.Name) &&
-			!ctx.IsSet(utils.RinkebyFlag.Name) &&
 			!ctx.IsSet(utils.GoerliFlag.Name) &&
 			!ctx.IsSet(utils.DeveloperFlag.Name) {
 			// Nope, we're really on mainnet. Bump that cache up!