Verification failed in Antithesis: backend.ConsistentIndex (1049) must be <= WAL.HardState.commit (1047)

Thanks to @nwnt work on https://github.com/etcd-io/etcd/pull/21972 we found another issue! Yey

This is not a new issue, was just masked as exit 2 code until we fixed it. Context: https://github.com/etcd-io/etcd/issues/21775

https://linuxfoundation.antithesis.com/search?search=v5veyJxIjp7Im4iOnsiciI6eyJoIjpbeyJoIjpbeyJjIjp0cnVlLCJmIjoibW9tZW50LnZ0aW1lIiwibyI6Im1hdGNoZXMiLCJ2IjoiMTIzLjE3ODY3MjEzOTk5ODUzIn1dLCJvIjoib3IifSx7ImgiOlt7ImMiOnRydWUsImYiOiJtb21lbnQuaW5wdXRfaGFzaCIsIm8iOiJtYXRjaGVzIiwidiI6Ii03OTgyNTUyMTI2MDg5MjA5NjU1In1dLCJvIjoib3IifV0sIm8iOiJhbmQifSwidCI6eyJnIjpmYWxzZSwibSI6IiJ9LCJ5Ijoibm9uZSJ9fSwicyI6IjM0MzA3MzNkZjRkNTdjOGI1MDYxZGEwZDUzNWJiZWMyLTU2LTE3In0

Start with the Antithesis verification failure and the context in issues #21775 and pull request #21972. Trace where backend.ConsistentIndex and WAL.HardState.commit are checked, then identify the relevant verification or failure path. Done means the reported invariant no longer fails under the Antithesis scenario.

Written by the indexing model from the issue text.