test: mask rc.local generator, broken on Jammy

On jammy it started to fail, it's not really needed and we install
an empty stub anyway, so just mask the generator

(cherry picked from commit 565916c245b53b49f5917f5326d21246f46ae3db)
(cherry picked from commit dfb007ffe0a9aa3a1d0f7930131b129fbaa2b3d9)

test/test-functions

@@ -1853,13 +1853,9 @@ strip_binaries() {
 }
 
 create_rc_local() {
-    dinfo "Create rc.local"
-    mkdir -p "${initdir:?}/etc/rc.d"
-    cat >"$initdir/etc/rc.d/rc.local" <<EOF
-#!/usr/bin/env bash
-exit 0
-EOF
-    chmod 0755 "$initdir/etc/rc.d/rc.local"
+    dinfo "Mask rc.local generator"
+    mkdir -p "${initdir:?}/etc/systemd/system-generators/"
+    ln -s /dev/null "$initdir/etc/systemd/system-generators/systemd-rc-local-generator"
 }
 
 install_execs() {