Rename Gradle target dcsClientDeb to buildDeb
Rename Gradle target dcsClientDeb to buildDeb

buildDeb is a built-in target from the nebula-ospackage Gradle plugin,
but it doesn't do anything. Setting `overwrite: true` lets us redefine
it.

kornysietsma/ci-spike-sample-app,kornysietsma/ci-spike-sample-app