Revert "test_minimizer: dnf5 wants --use-host-config"

This reverts commit b99f9ba.

dnf5 is not the default in Fedora 39/40 so this doesn't work.

tests/image-minimizer/test_minimizer.py

@@ -8,7 +8,7 @@
 class MinimizerTestCase(unittest.TestCase):
     def test_minimizer_ok(self):
         with tempfile.TemporaryDirectory(prefix="minimize.test.") as rootdir:
-            check_call(["dnf", "--use-host-config", "--installroot", rootdir, "install", "-y", \
+            check_call(["dnf", "--releasever=/", "--installroot", rootdir, "install", "-y", \
                         "filesystem", "tzdata"])
 
             im = ImageMinimizer("./tests/image-minimizer/im-script.txt", rootdir, False, False)