Attempt to fix flaky basic sim test

[jimmygchen]

Issue Addressed

Fix target_peer config for basic_sim, so a node doesn't disconnected by peers because of TooManyPeers.

I think the test fails when enough nodes disconnect one of the nodes and messages from that node don't get propagated to the network correctly.

[jimmygchen]

The test failed again, but I think the fix is still valid.

The target_peer issue was the reason this run failed: https://github.com/sigp/lighthouse/actions/runs/9986823946/job/27600016474

The current run is failing due to the new node (node_6) having a non-optimistic head block. Investigating.

UPDATE: the above is not correct actually, node_6 has no validators attached so it wouldn't contribute to sync message issues.

The error is

2024-07-19T02:32:12.8166404Z called `Result::unwrap()` on an `Err` value: "Sync aggregate at slot 17 was not full, got: 20, expected: 32"

so it looks like the sync contributions were not published for all signers, this is something we've experienced before and usually happens around fork boundaries.

[michaelsproul]

@mergify queue

[mergify]

queue

🛑 The pull request has been removed from the queue default

The queue conditions cannot be satisfied due to failing checks.

You can take a look at Queue: Embarked in merge queue check runs for more details.

In case of a failure due to a flaky test, you should first retrigger the CI.
Then, re-embark the pull request into the merge queue by posting the comment
@mergifyio refresh on the pull request.

[jimmygchen]

@mergify requeue

[mergify]

requeue

✅ This pull request will be re-embarked automatically

The followup queue command will be automatically executed to re-embark the pull request

[mergify]

queue

✅ The pull request has been merged automatically

The pull request has been merged automatically at 256f012