Revert "revert sysusers setting [RHBZ#1740545]"

This reverts commit ad7551f.

Provide users/groups via `/usr/lib/sysusers.d`. This is going
to be handled by RPM.

Relates to fedora-copr/copr#2789

mock-core-configs/mock-core-configs.spec

@@ -51,6 +51,9 @@ Rocky Linux and various other specific or combined chroots.
 
 %install
 mkdir -p %{buildroot}%{_sysusersdir}
+%if 0%{?fedora} > 39 || 0%{?rhel} > 8
+cp -a mock.conf %{buildroot}%{_sysusersdir}
+%endif
 
 mkdir -p %{buildroot}%{_sysconfdir}/mock/eol/templates
 mkdir -p %{buildroot}%{_sysconfdir}/mock/templates
@@ -149,6 +152,9 @@ fi
 %license COPYING
 %doc README
 %ghost %config(noreplace,missingok) %{_sysconfdir}/mock/default.cfg
+%if 0%{?fedora} > 39 || 0%{?rhel} > 8
+%config(noreplace) %{_sysusersdir}/mock.conf
+%endif
 
 %changelog
 * Fri Apr 05 2024 Jakub Kadlcik <[email protected]> 40.3-1