container-toolbox: Restore the tests
    
    The tests can't be run inside the '%post --nochroot' section because
    the paths being tested don't include the /mnt/sysimage prefix.  The
    tests must be run in the %post section without --nochroot so that they
    are run inside the chroot environment.
    
    The translations for the RPM manuals were removed upstream during the
    RPM 4.19 development cycle [1].  So, replace them with rpm2cpio(8),
    which is another popular command shipped by the rpm package.
    
    [1] RPM commit 4df74a9644b18136
        https://github.com/rpm-software-management/rpm/commit/4df74a9644b18136
        https://github.com/rpm-software-management/rpm/pull/2245
    
    https://pagure.io/fedora-kickstarts/pull-request/1008