l2geth: remove layer of indirection with state manager

This PR removes the assignment of a pointer to the
state manager abi and just directly uses it instead.
There is an assumption that the state manager abi exists,
but this check happens at startup time, when the abis are
pulled from the state dump.

.changeset/five-toys-impress.md

+---
+'@eth-optimism/l2geth': patch
+---
+
+Remove layer of indirection in `callStateManager`

l2geth/core/vm/ovm_state_manager.go

@@ -34,10 +34,7 @@ var funcs = map[string]stateManagerFunction{
 }
 
 func callStateManager(input []byte, evm *EVM, contract *Contract) (ret []byte, err error) {
-	rawabi := evm.Context.OvmStateManager.ABI
-	abi := &rawabi
-
-	method, err := abi.MethodById(input)
+	method, err := evm.Context.OvmStateManager.ABI.MethodById(input)
 	if err != nil {
 		return nil, fmt.Errorf("cannot find method id %s: %w", input, err)
 	}