Switch to libreswan-minimal in the gateway

This reduces the image size (185MiB instead of 203MiB) and drops all
the systemd dependencies.

Signed-off-by: Stephen Kitt <skitt@redhat.com>

Author: skitt

package/Dockerfile.submariner-gateway

@@ -24,8 +24,10 @@ COPY package/dnf_install /
 # kmod is required so that libreswan can load modules
 RUN /dnf_install -a ${TARGETPLATFORM} -v ${FEDORA_VERSION} -r /output/gateway \
     glibc bash glibc-minimal-langpack coreutils-single \
-    libcurl-minimal iproute libreswan kmod \
-    openssl nss-tools
+    libcurl-minimal iproute libreswan-minimal kmod \
+    openssl procps-ng nss-tools
+
+# util-linux-core
 
 FROM scratch
 ARG SOURCE