cmd, core: remove calaveras testnet (#23366)

Removes references to the short-lived Calaveras testnet

core/genesis_test.go

@@ -185,10 +185,6 @@ func TestGenesisHashes(t *testing.T) {
 			genesis: DefaultRinkebyGenesisBlock(),
 			hash:    params.RinkebyGenesisHash,
 		},
-		{
-			genesis: DefaultCalaverasGenesisBlock(),
-			hash:    params.CalaverasGenesisHash,
-		},
 	}
 	for i, c := range cases {
 		b := c.genesis.MustCommit(rawdb.NewMemoryDatabase())