WIP: port a test to use the multi-node framework.
Further WIP-saving.
Add a mechanism for federation to run multiple nodes in one distributed system, and thus port the rest of the mutli-node tests. There is still a great deal of detritus to be removed...
Port all the in-broker tests.
Remove some no-longer-needed stuff
Add needed dependency so we can test from clean.
Easier to just override this than tweak the umbrella.
API change, slight cleanup.
Don't assume paths.
Merge bug26162