tests, les, eth: remove mentions of deprecated Morden testnet (#23570)

* remove morden

* Update commons.go

* Update handler.go

* empty commit to make appveyor happy

eth/protocols/eth/handler.go

@@ -127,7 +127,7 @@ func MakeProtocols(backend Backend, network uint64, dnsdisc enode.Iterator) []p2
 // NodeInfo represents a short summary of the `eth` sub-protocol metadata
 // known about the host peer.
 type NodeInfo struct {
-	Network    uint64              `json:"network"`    // Ethereum network ID (1=Frontier, 2=Morden, Ropsten=3, Rinkeby=4)
+	Network    uint64              `json:"network"`    // Ethereum network ID (1=Mainnet, Ropsten=3, Rinkeby=4, Goerli=5)
 	Difficulty *big.Int            `json:"difficulty"` // Total difficulty of the host's blockchain
 	Genesis    common.Hash         `json:"genesis"`    // SHA3 hash of the host's genesis block
 	Config     *params.ChainConfig `json:"config"`     // Chain configuration for the fork rules