all: remove Kiln testnet (#26522)

Kiln was deprecated after the merge.

core/genesis.go

@@ -431,8 +431,6 @@ func (g *Genesis) configOrDefault(ghash common.Hash) *params.ChainConfig {
 		return params.RinkebyChainConfig
 	case ghash == params.GoerliGenesisHash:
 		return params.GoerliChainConfig
-	case ghash == params.KilnGenesisHash:
-		return DefaultKilnGenesisBlock().Config
 	default:
 		return params.AllEthashProtocolChanges
 	}
@@ -581,16 +579,6 @@ func DefaultSepoliaGenesisBlock() *Genesis {
 	}
 }
 
-// DefaultKilnGenesisBlock returns the kiln network genesis block.
-func DefaultKilnGenesisBlock() *Genesis {
-	g := new(Genesis)
-	reader := strings.NewReader(KilnAllocData)
-	if err := json.NewDecoder(reader).Decode(g); err != nil {
-		panic(err)
-	}
-	return g
-}
-
 // DeveloperGenesisBlock returns the 'geth --dev' genesis block.
 func DeveloperGenesisBlock(period uint64, gasLimit uint64, faucet common.Address) *Genesis {
 	// Override the default period to the user requested one