chkconfig in RPM server scriptlets

chkconfig --add and --del [might] invoke /sbin/insserv
and even if chkconfig exists, insserv might not (SLES15).

Ignore chkconfig --del errors - it's a "best effort" cleanup anyway

support-files/rpm/server-preun.sh

@@ -9,7 +9,7 @@ if [ $1 = 0 ] ; then
                 %{_sysconfdir}/init.d/mysql stop > /dev/null
         fi
         if [ -x /sbin/chkconfig ] ; then
-                /sbin/chkconfig --del mysql > /dev/null 2>&1
+                /sbin/chkconfig --del mysql > /dev/null 2>&1 || :
         fi
 fi