[FEATURE] Only download zips when needed in build.gradle

[downsrob]

Is your feature request related to a problem?
Currently, job scheduler and job scheduler/ism backwards compatibility testing zips are downloaded when any gradle task is executed. The reason for this is that the integration test clusters are configured before any gradle tasks are run.

What solution would you like?
These zips should not be downloaded for tasks such as ./gradlew detekt, and the backwards compatibility zips should only be downloaded for bwc testing. To get rid of this unnecessary work, the build.gradle needs to be refactored to only do the necessary cluster configuration when the requested gradle task requires it.

What alternatives have you considered?
The backwards compatibility zips might not need to be refreshed if already downloaded, as the file is unlikely to change, this would at least reduce some of the configuration downloading with each task.

[downsrob]

Fixed with this PR #334