server.it.weekly jenkins job runs out of disk space on Windows

This job is failing on Windows:
https://dev-platform-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/server.it.weekly/

It's because it runs out of disk space.
The windows instances have (I believe) 30GB of disk space. This is set up in our openstack instance by eng-ops:
https://ci-rhos.centralci.eng.rdu2.redhat.com/dashboard/
If we wanted more space, we would need to ask eng ops to change this. But it's probably the same for all other users, so I don't think they would change it easily. And in any case, it should be enough.

The main thing is that we need to reduce the space the tests are using.
They download all the runtimes via the itests pom:
https://github.com/jbosstools/jbosstools-server/blob/master/as/itests/pom.xml#L122

The main problem is that this happens 4 times:
3.5G ./org.jboss.tools.as.management.itests/target/requirements
3.5G ./org.jboss.tools.as.itests/target/requirements
3.5G ./target/requirements
3.5G ./org.jboss.tools.as.ui.bot.itests/target/requirements

Fortunately this doesn't mean that all the servers are really downloaded 4 times - they are downloaded once and stored in the local maven download cache. But then the zips are copied over for each of the modules and unzipped.

So, there are several options:

a) Get rid of the zips once they're unzipped - that would save half the space. Unfortunately the download plugin does not support this:
https://github.com/maven-download-plugin/maven-download-plugin

b) Delete the requirements dir for each module at the end of the maven module lifecycle. This might be doable, needs investigating.

c) Change the overall setup so that only one download is needed for all the tests - i.e. the child modules don't inherit the download plugin call, but instead use the downloaded runtimes from the higher pom (itests)