tests/e2e-upgrade: update grub to Fedora 42 versions

Fedora CoreOS is now on Fedora 42 so it makes sense to test
Fedora 42 versions of the GRUB packages here.

Author: dustymabe

tests/e2e-update/e2e-update.sh

@@ -84,15 +84,15 @@ undo_manifest_fork() {
 if test -z "${e2e_skip_build:-}"; then
     echo "Building starting image"
     rm -f ${overrides}/rpm/*.rpm
-    # Version from F41 GA
-    add_override grub2-2.12-4.fc41
+    # Version from F42 prior to GA
+    add_override grub2-2.12-26.fc42
     runv cosa build
     prev_image=$(runv cosa meta --image-path qemu)
     create_manifest_fork
     rm -f ${overrides}/rpm/*.rpm
     echo "Building update ostree"
-    # Version queued in current updates
-    add_override grub2-2.12-10.fc41
+    # Latest (current) version in F42
+    add_override grub2-2.12-28.fc42
     mv ${test_tmpdir}/yumrepo/packages/$(arch)/*.rpm ${overrides}/rpm/
     # Only build ostree update
     runv cosa build ostree