rolling update: fix undefined jewel_minor_update failure

rolling update: fix undefined jewel_minor_update failure

Variables set at the play level with ``vars`` do
not carry over into the next play in the playbook.

The var jewel_minor_update was set in a previous play but
used in this one and was failing because it was not defined.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1544029

Signed-off-by: Andrew Schoen <aschoen@redhat.com>
(cherry picked from commit 699c777e680655be12f53cabed626b28623f8160)
Signed-off-by: Sébastien Han <seb@redhat.com>