op-e2e: re-enable p2p gossip tests

See p2p test-skip in https://github.com/ethereum-optimism/optimism/pull/16855/files

The devstack does have p2p connect/disconnect abilities, but the p2p testing only happens in older multi-supervisor tests, which might not persist due to interop changes.

We should create a standard devstack test that asserts there is an active p2p connection between two L2 CL nodes of the same chain, and that blocks propagate as expected.