images: Drop explicit libssh from Fedora

The explicit runtime dependency has been unnecessary since commit
9a6962d, as installing cockpit-bridge brings this in as a dependency.
It will actually drop from the image after the next Cockpit release, as
it was dropped in cockpit-project/cockpit#19441

Also drop it from the base container.

images/scripts/fedora.setup

@@ -55,7 +55,6 @@ glibc-langpack-pt \
 glib-networking \
 grubby \
 json-glib \
-libssh \
 NetworkManager-team \
 openssl \
 PackageKit \

images/scripts/lib/base/setup.sh

@@ -2,5 +2,5 @@
 set -eu
 
 dnf -y update
-dnf install -y sed findutils glib-networking json-glib libssh openssl python3 systemd
+dnf install -y sed findutils glib-networking json-glib openssl python3 systemd
 dnf clean all