e2e tests: stop using UBI images

Red Hat registry is too unreliable. (As of this writing
in January 2023, quay.io is not much better, but this is
a new flake. Ubi has been flaking for a year or more).

Instead of UBI, use the new systemd-image added to system tests
in #16814. Since this reduces the number of cached images,
a few unrelated tests (image count) need to be tweaked.

And, sigh, Fedora systemd colorizes boot messages by default,
causing a failure where we don't see an expected Reached Target
message. I don't want to rely on ASCII formatting codes, so
I've updated the build-systemd-image script so it disables
systemd colors, and have built a new systemd-image:20230106.
Made a few small usability improvements to the script as well.

Closes: #16695

Signed-off-by: Ed Santiago <santiago@redhat.com>

test/e2e/run_selinux_test.go

@@ -319,7 +319,7 @@ var _ = Describe("Podman run", func() {
 	})
 
 	It("podman test init labels", func() {
-		session := podmanTest.Podman([]string{"create", UBI_INIT, "/sbin/init"})
+		session := podmanTest.Podman([]string{"create", SYSTEMD_IMAGE, "/sbin/init"})
 		session.WaitWithDefaultTimeout()
 		Expect(session).Should(Exit(0))
 		cid := session.OutputToString()