MDEV-25240 minor upgrade does not perform server restart

we need to stop server instance on upgrade, but it may be started either by SysV init script or by SystemD.
this commit adds `mysql` target to `systemctl stop` call.
`mysql` may be the name of initscript or an alias while `mariadb` is
a systemd unit file.

support-files/rpm/server-posttrans.sh

 if [ -r %{restart_flag} ] ; then
   rm %{restart_flag}
+  # only restart the server if it was alredy running
   if [ -x /usr/bin/systemctl ] ; then
     /usr/bin/systemctl daemon-reload > /dev/null 2>&1
-    /usr/bin/systemctl try-restart mariadb.service > /dev/null 2>&1
+    if [ /usr/bin/systemctl is-active mysql ]; then
+      /usr/bin/systemctl restart mysql > /dev/null 2>&1
+    else
+      /usr/bin/systemctl try-restart mariadb.service > /dev/null 2>&1
+    fi
+  # not a systemd-enabled environment, use SysV startup script
   elif %{_sysconfdir}/init.d/mysql status > /dev/null 2>&1; then
-    # only restart the server if it was alredy running
-    %{_sysconfdir}/init.d/mysql restart
+    %{_sysconfdir}/init.d/mysql restart > /dev/null 2>&1
   fi
 fi