Use blocks v3 endpoint in the VC

lighthouse/tests/validator_client.rs

@@ -421,6 +421,21 @@ fn no_doppelganger_protection_flag() {
         .run()
         .with_config(|config| assert!(!config.enable_doppelganger_protection));
 }
+#[test]
+fn produce_block_v3_flag() {
+    CommandLineTest::new()
+        .flag("produce-block-v3", None)
+        .run()
+        .with_config(|config| assert!(config.produce_block_v3));
+}
+
+#[test]
+fn no_produce_block_v3_flag() {
+    CommandLineTest::new()
+        .run()
+        .with_config(|config| assert!(!config.produce_block_v3));
+}
+
 #[test]
 fn no_gas_limit_flag() {
     CommandLineTest::new()