clevis: simplify sysusers.d fragment by using default 'nologin' shell

This tweaks the existing sysuser.d fragment in order to simplify it.
The 'nologin' shell is the documented systemd default, so there is
no need to explicitly specify it.
This change allows better handling of default vs custom shell in the
macro logic which bridges between `systemd-sysusers` and `useradd`.

clevis.spec

@@ -1,6 +1,6 @@
 Name:           clevis
 Version:        18
-Release:        9%{?dist}
+Release:        10%{?dist}
 Summary:        Automated decryption framework
 
 License:        GPLv3+
@@ -192,6 +192,9 @@ exit 0
 systemctl preset %{name}-luks-askpass.path >/dev/null 2>&1 || :
 
 %changelog
+* Fri Aug 05 2022 Luca BRUNO <lucab@lucabruno.net> - 18-10
+- Simplify sysusers.d fragment by using default 'nologin' shell
+
 * Wed Jul 20 2022 Fedora Release Engineering <releng@fedoraproject.org> - 18-9
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_37_Mass_Rebuild
 

clevis.sysusers

@@ -1 +1 @@
-u clevis - "Clevis Decryption Framework unprivileged user" /var/cache/clevis /usr/sbin/nologin
+u clevis - "Clevis Decryption Framework unprivileged user" /var/cache/clevis -