test_display.sh: tweak for images with no INSTALL label
test_display.sh: tweak for images with no INSTALL label

Now that PR #217 is merged, running `atomic install` on images without
INSTALL labels become noops. Test 5 of test_display.sh reflects this new
behaviour.

charliedrage/atomic,charliedrage/atomic,rh-atomic-bot/atomic,cdrage/atomic,sallyom/atomic,rh-atomic-bot/atomic,cdrage/atomic,sallyom/atomic