[sdk-manage] Change i486 target creation until sb2 is fixed

Revert "[sdk-manage] Define the target rootfs as tools dir for i486 targets"

This reverts commit c1deef7abb960787e46c1a9e35ccdf725b065374.
[mb2] Clean RPMS directory before creating new rpms

Signed-off-by: Juha Kallioinen <juha.kallioinen@jolla.com>