Remove old target platforms.

Having so many is plain confusing and all of them are not supported. I
still left oxygen/photon/2020-03/2020-09 as they all seem used in some
way to me.

Change-Id: I184d579d0c252aa08bc8eb0d11e4e9a14e49f1d3
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>
5 files changed