* Don't use state sync for nodes starting at initial height.
* Also remove stopped containers when cleaning up.
* Start nodes in order of startAt, mode, name to avoid full nodes starting before their seeds.
* Tweak network waiting to avoid halts caused by validator changes and perturbations.
* Disable most tests for seed nodes, which aren't always able to join consensus.
* Disable `blockchain/v2` due to known bugs.
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.
