post: Re-instate systemd ProtectHome/ProtectSystem and PrivateTmp

Following the `fedora-atomic` version:
https://pagure.io/fedora-atomic/c/174e04cb6c268ce32135e8e70194b3ee42fb6f9d?branch=master

post.sh

@@ -6,6 +6,3 @@ set -xeuo pipefail
 # aspects of that have been fixed, but apparently this is still
 # necessary, and generally makes things less finicky
 echo 'Storage=persistent' >> /etc/systemd/journald.conf
-
-# Work around https://github.com/systemd/systemd/issues/4082
-find /usr/lib/systemd/system/ -type f -exec sed -i -e '/^PrivateTmp=/d' -e '/^Protect\(Home\|System\)=/d' {} \;