test(e2e): test missed l1 publishing under pipelining

[spalladino]

End-to-end test for the "missed L1 publish" scenario under proposer pipelining.

Each of 4 nodes holds exactly one validator key. We pick four consecutive slots
(slotZero, slotOne, slotTwo, slotThree) such that the proposers for slotOne, slotTwo, and
slotThree are three distinct validators, then warp to one L1 block before slotZero begins.

The proposer for slotOne is configured to skip its L1 publish.
With pipelining, the proposer for slot N+1 builds and gossips its checkpoint during slot N,
then publishes that checkpoint to L1 during slot N+1. So gossip-driven proposed chain
advances arrive one slot earlier than the L1-driven checkpointed advance.

Expected behavior:

• During slotZero, the pipelined proposer for slotOne gossips its build → every node's
  proposed tip advances to a block at slotOne.
• During slotOne, the pipelined proposer for slotTwo gossips on top of the slotOne proposal →
  proposed advances to a block at slotTwo. Meanwhile the proposer for slotOne attempts L1
  publish but is configured to skip it, so no checkpoint lands.
• When slotOne ends with no checkpoint mined, every node's archiver prunes the
  uncheckpointed slotOne and slotTwo blocks; we verify rollback via the prune event.
  We then re-enable publishing on the formerly suppressed node so recovery can proceed.
• During slotTwo, the pipelined proposer for slotThree builds on top of the (now genesis)
  checkpointed tip → proposed advances again.
• During slotThree, that pipelined work is published → checkpointed finally advances.