Gradle's finalizedBy on tasks only ensures one task runs after another,
but not immediately after. This is problematic for our integration tests
since it allows multiple project's integ test clusters to be
simultaneously. While this has not been a problem thus far (gradle 2.13
happened to keep the finalizedBy tasks close enough that no clusters
were running in parallel), with gradle 3.3 the task graph generation has
changed, and numerous clusters may be running simultaneously, causing
memory pressure, and thus generally slower tests, or even failure if the
system has a limited amount of memory (eg in a vagrant host).
This commit reworks how integ tests are configured. It adds an
`integTestCluster` extension to gradle which is equivalent to the current
`integTest.cluster` and moves the rest test runner task to
`integTestRunner`. The `integTest` task is then just a dummy task,
which depends on the cluster runner task, as well as the cluster stop
task. This means running `integTest` in one project will both run the
rest tests, and shut down the cluster, before running `integTest` in
another project.
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.