Tweak rebuild policy

Since using transitive rebuild could lead to many rebuilds which don't add
much value, instead use direct rebuild to ensure packages in the direct
dependency chain are rebuild. Let the comment about transitive rebuilds
as it still applies and can be used with caution.

See: https://openbuildservice.org/help/manuals/obs-user-guide/cha-obs-build-scheduling-and-dispatching#id-1.2.10.14.5.7



Signed-off-by: Walter Lozano <walter.lozano@collabora.com>