ci: switch to fedora-35 on i386 on Packit

systemd seems to be failing to compile there with gcc-12 but considering
that gcc-12 hasn't been released yet it doesn't seem to make sense
to add workarounds to get it to compile there. Until gcc-12 is
stabilized it should be enough to build systemd on fedora-35 to
make sure it's buildable on i386.

.packit.yml

@@ -38,6 +38,6 @@ jobs:
   metadata:
     targets:
     - fedora-rawhide-aarch64
-    - fedora-rawhide-i386
+    - fedora-35-i386
     - fedora-rawhide-ppc64le
     - fedora-rawhide-x86_64