In #5488 the E2E testnet generator changed to setting explicit `StartAt` heights for initial nodes. This broke the runner, which expected all initial nodes to have `StartAt: 0`, as well as validator set scheduling in the generator. Testnet loading now normalizes initial nodes to have `StartAt: 0`.
This also tweaks waiting for misbehavior heights to only use an additional wait if there actually is any misbehavior in the testnet, and to output information when waiting.
Closes#5291. Adds a randomized testnet generator. Nightly CI job will be submitted separately. A few of the testnets can be a bit flaky, even after disabling known-faulty behavior and making minor tweaks, and the larger networks may be too resource-intensive to run in CI - this will be optimized separately.
This was a missing test case from the old P2P tests removed in #5453, which makes sure that all nodes are able to peer with each other regardless of how they discover peers.
Fixes#2795, since the default CI testnet uses a combination of (partially meshed) persistent peers and PEX-based seed nodes.
Partial fix for #5291.
This adds a basic set of test cases for core network invariants. Although small, it is sufficient to replace and extend the current set of P2P tests. Further test cases can be added later.