We kept `netty_3` as a fallback in the 5.x series but now that master
is 6.0 we don't need this or in other words all issues coming up with
netty 4 will be blockers for 6.0.
This change adds back the multi node smoke test, as well as making the
cluster formation for any test allow multiple nodes. The main changes in
cluster formation are abstracting out the node specific configuration to
a helper struct, as well as making a single wait task that waits for all
nodes after their start tasks have run. The output on failure was also
improved to log which node's info is being printed.
Nik Everett
Simon Willnauer
Ryan Ernst