update-ids-ruleset: Always drop the lock file if it has been created during runtime.

update-ids-ruleset: Always drop the lock file if it has been created during runtime.

In some situations or if an error happened, the lock file could be
keep on the system. In such a case the IDS page would be locked forever
until user interaction or reboot of the system.

Now the script checks if it has created such a lock and release it when
the script exists.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
Reviewed-by: Michael Tremer <michael.tremer@ipfire.org>
Acked-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>