container build: use transient containers for advisory_check

using podman run leaves containers and/or images lying around; if
the thing being tested is big enough, we can wind up with enough
that podman just stops working (I saw this while testing the
python 3.13 side tag). To avoid this, use podman run --rm, which
clears up the container/image after the command is run.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

tests/_container_build_kiwi.pm

@@ -119,7 +119,7 @@ sub run {
     my $imgspec = "localhost/fedora:${mockver}";
     validate_script_output "podman run ${imgspec} echo Hello-World", sub { m/Hello-World/ };
     # do advisory_check_nonmatching_packages inside the container
-    advisory_check_nonmatching_packages(wrapper => "podman run ${imgspec}");
+    advisory_check_nonmatching_packages(wrapper => "podman run --rm ${imgspec}");
     # wipe the temp file so it doesn't interfere with the same check
     # on the host
     assert_script_run "rm -f /tmp/installedupdatepkgs.txt";