Reorder ostree and ostree_installer phases
    
    osbuild phase needs to wait for ostree phase in some cases, this patch
    makes the various image build phases waiting for ostree phase, it may
    introduce some slowdown, but it's still faster than the version before
    PR#1790.
    
    JIRA: RHELCMP-14349
    Fixes: https://pagure.io/pungi/issue/1816
    Signed-off-by: Haibo Lin <hlin@redhat.com>