Clean Upstream CentOS repos which comes with centos-release pkg
Clean Upstream CentOS repos which comes with centos-release pkg

We need to clean RPM chroot each time on installing packages from
$(SANDBOX_PACKAGES), since some of them can "bring" centos-release
as dependency

Change-Id: I274f3e3675d327c700262058682200d7781ff1b9
Related-bug: #1541871

SergK/fuel-main,SergK/fuel-main,stackforge/fuel-main,stackforge/fuel-main,SergK/fuel-main,stackforge/fuel-main