Meta plugins existed only for a short time, in order to enable breaking
up x-pack into multiple plugins. However, now that x-pack is no longer
installed as a plugin, the need for them has disappeared. This commit
removes the meta plugins infrastructure.
This commit removes xpack from being a meta-plugin-as-a-module.
It also fixes a couple tests which were missing task dependencies, which
failed once the gradle execution order changed.
Add the oss tar distribution to the packaging test plugin. Test the oss
tar distribution in the core packaging tests, and the non-oss tar
distribution in the x-pack packaging tests.
This commit makes x-pack a module and adds it to the default
distrubtion. It also creates distributions for zip, tar, deb and rpm
which contain only oss code.