core/vm: rename RANDOM to PREVRANDAO (#25691)

See: https://github.com/ethereum/EIPs/blob/master/EIPS/eip-4399.md

>  This EIP supplants the semantics of the return value of existing DIFFICULTY (0x44) opcode and renames the opcode to PREVRANDAO (0x44).

core/vm/evm.go

@@ -75,7 +75,7 @@ type BlockContext struct {
 	Time        *big.Int       // Provides information for TIME
 	Difficulty  *big.Int       // Provides information for DIFFICULTY
 	BaseFee     *big.Int       // Provides information for BASEFEE
-	Random      *common.Hash   // Provides information for RANDOM
+	Random      *common.Hash   // Provides information for PREVRANDAO
 }
 
 // TxContext provides the EVM with information about a transaction.

core/vm/jump_table.go

@@ -80,7 +80,7 @@ func validate(jt JumpTable) JumpTable {
 
 func newMergeInstructionSet() JumpTable {
 	instructionSet := newLondonInstructionSet()
-	instructionSet[RANDOM] = &operation{
+	instructionSet[PREVRANDAO] = &operation{
 		execute:     opRandom,
 		constantGas: GasQuickStep,
 		minStack:    minStack(0, 1),

core/vm/opcodes.go

@@ -99,6 +99,7 @@ const (
 	NUMBER      OpCode = 0x43
 	DIFFICULTY  OpCode = 0x44
 	RANDOM      OpCode = 0x44 // Same as DIFFICULTY
+	PREVRANDAO  OpCode = 0x44 // Same as DIFFICULTY
 	GASLIMIT    OpCode = 0x45
 	CHAINID     OpCode = 0x46
 	SELFBALANCE OpCode = 0x47
@@ -280,7 +281,7 @@ var opCodeToString = map[OpCode]string{
 	COINBASE:    "COINBASE",
 	TIMESTAMP:   "TIMESTAMP",
 	NUMBER:      "NUMBER",
-	DIFFICULTY:  "DIFFICULTY", // TODO (MariusVanDerWijden) rename to RANDOM post merge
+	DIFFICULTY:  "DIFFICULTY", // TODO (MariusVanDerWijden) rename to PREVRANDAO post merge
 	GASLIMIT:    "GASLIMIT",
 	CHAINID:     "CHAINID",
 	SELFBALANCE: "SELFBALANCE",