Rename random to prev_randao (#3040)

## Issue Addressed

As discussed on last-night's consensus call, the testnets next week will target the [Kiln Spec v2](https://hackmd.io/@n0ble/kiln-spec).

Presently, we support Kiln V1. V2 is backwards compatible, except for renaming `random` to `prev_randao` in:

- https://github.com/ethereum/execution-apis/pull/180
- https://github.com/ethereum/consensus-specs/pull/2835

With this PR we'll no longer be compatible with the existing Kintsugi and Kiln testnets, however we'll be ready for the testnets next week. I raised this breaking change in the call last night, we are all keen to move forward and break things.

We now target the [`merge-kiln-v2`](https://github.com/MariusVanDerWijden/go-ethereum/tree/merge-kiln-v2) branch for interop with Geth. This required adding the `--http.aauthport` to the tester to avoid a port conflict at startup.

### Changes to exec integration tests

There's some change in the `merge-kiln-v2` version of Geth that means it can't compile on a vanilla Github runner. Bumping the `go` version on the runner solved this issue.

Whilst addressing this, I refactored the `testing/execution_integration` crate to be a *binary* rather than a *library* with tests. This means that we don't need to run the `build.rs` and build Geth whenever someone runs `make lint` or `make test-release`. This is nice for everyday users, but it's also nice for CI so that we can have a specific runner for these tests and we don't need to ensure *all* runners support everything required to build all execution clients.

## More Info

- [x] ~~EF tests are failing since the rename has broken some tests that reference the old field name. I have been told there will be new tests released in the coming days (25/02/22 or 26/02/22).~~

beacon_node/beacon_chain/tests/payload_invalidation.rs

@@ -231,8 +231,10 @@ fn valid_invalid_syncing() {
 /// `latest_valid_hash`.
 #[test]
 fn invalid_payload_invalidates_parent() {
-    let mut rig = InvalidPayloadRig::new();
+    let mut rig = InvalidPayloadRig::new().enable_attestations();
     rig.move_to_terminal_block();
+    rig.import_block(Payload::Valid); // Import a valid transition block.
+    rig.move_to_first_justification(Payload::Syncing);
 
     let roots = vec![
         rig.import_block(Payload::Syncing),
@@ -258,6 +260,7 @@ fn invalid_payload_invalidates_parent() {
 fn justified_checkpoint_becomes_invalid() {
     let mut rig = InvalidPayloadRig::new().enable_attestations();
     rig.move_to_terminal_block();
+    rig.import_block(Payload::Valid); // Import a valid transition block.
     rig.move_to_first_justification(Payload::Syncing);
 
     let justified_checkpoint = rig.head_info().current_justified_checkpoint;
@@ -305,7 +308,9 @@ fn pre_finalized_latest_valid_hash() {
 
     let mut rig = InvalidPayloadRig::new().enable_attestations();
     rig.move_to_terminal_block();
-    let blocks = rig.build_blocks(num_blocks, Payload::Syncing);
+    let mut blocks = vec![];
+    blocks.push(rig.import_block(Payload::Valid)); // Import a valid transition block.
+    blocks.extend(rig.build_blocks(num_blocks - 1, Payload::Syncing));
 
     assert_eq!(rig.head_info().finalized_checkpoint.epoch, finalized_epoch);
 
@@ -330,7 +335,11 @@ fn pre_finalized_latest_valid_hash() {
     for i in E::slots_per_epoch() * finalized_epoch..num_blocks {
         let slot = Slot::new(i);
         let root = rig.block_root_at_slot(slot).unwrap();
-        assert!(rig.execution_status(root).is_not_verified());
+        if slot == 1 {
+            assert!(rig.execution_status(root).is_valid());
+        } else {
+            assert!(rig.execution_status(root).is_not_verified());
+        }
     }
 }
 
@@ -344,7 +353,10 @@ fn latest_valid_hash_will_validate() {
 
     let mut rig = InvalidPayloadRig::new().enable_attestations();
     rig.move_to_terminal_block();
-    let blocks = rig.build_blocks(4, Payload::Syncing);
+
+    let mut blocks = vec![];
+    blocks.push(rig.import_block(Payload::Valid)); // Import a valid transition block.
+    blocks.extend(rig.build_blocks(4, Payload::Syncing));
 
     let latest_valid_root = rig
         .block_root_at_slot(Slot::new(LATEST_VALID_SLOT))
@@ -357,7 +369,7 @@ fn latest_valid_hash_will_validate() {
 
     assert_eq!(rig.head_info().slot, LATEST_VALID_SLOT);
 
-    for slot in 0..=4 {
+    for slot in 0..=5 {
         let slot = Slot::new(slot);
         let root = if slot > 0 {
             // If not the genesis slot, check the blocks we just produced.
@@ -386,7 +398,9 @@ fn latest_valid_hash_is_junk() {
 
     let mut rig = InvalidPayloadRig::new().enable_attestations();
     rig.move_to_terminal_block();
-    let blocks = rig.build_blocks(num_blocks, Payload::Syncing);
+    let mut blocks = vec![];
+    blocks.push(rig.import_block(Payload::Valid)); // Import a valid transition block.
+    blocks.extend(rig.build_blocks(num_blocks, Payload::Syncing));
 
     assert_eq!(rig.head_info().finalized_checkpoint.epoch, finalized_epoch);
 
@@ -408,7 +422,11 @@ fn latest_valid_hash_is_junk() {
     for i in E::slots_per_epoch() * finalized_epoch..num_blocks {
         let slot = Slot::new(i);
         let root = rig.block_root_at_slot(slot).unwrap();
-        assert!(rig.execution_status(root).is_not_verified());
+        if slot == 1 {
+            assert!(rig.execution_status(root).is_valid());
+        } else {
+            assert!(rig.execution_status(root).is_not_verified());
+        }
     }
 }
 
@@ -421,6 +439,7 @@ fn invalidates_all_descendants() {
 
     let mut rig = InvalidPayloadRig::new().enable_attestations();
     rig.move_to_terminal_block();
+    rig.import_block(Payload::Valid); // Import a valid transition block.
     let blocks = rig.build_blocks(num_blocks, Payload::Syncing);
 
     assert_eq!(rig.head_info().finalized_checkpoint.epoch, finalized_epoch);
@@ -493,6 +512,7 @@ fn switches_heads() {
 
     let mut rig = InvalidPayloadRig::new().enable_attestations();
     rig.move_to_terminal_block();
+    rig.import_block(Payload::Valid); // Import a valid transition block.
     let blocks = rig.build_blocks(num_blocks, Payload::Syncing);
 
     assert_eq!(rig.head_info().finalized_checkpoint.epoch, finalized_epoch);
@@ -571,8 +591,9 @@ fn invalid_during_processing() {
 
 #[test]
 fn invalid_after_optimistic_sync() {
-    let mut rig = InvalidPayloadRig::new();
+    let mut rig = InvalidPayloadRig::new().enable_attestations();
     rig.move_to_terminal_block();
+    rig.import_block(Payload::Valid); // Import a valid transition block.
 
     let mut roots = vec![
         rig.import_block(Payload::Syncing),