Pull request: fix schedule timezone

Updates #6401

Squashed commit of the following:

commit 0ed83fd52fe8cf9bd5a8d438e81534799a7fdd83
Author: Ildar Kamalov <ik@adguard.com>
Date:   Fri Nov 10 16:09:04 2023 +0300

    ADG-7720 fix schedule timezone

client/src/components/Filters/Services/ScheduleForm/Modal.js

@@ -81,6 +81,10 @@ export const Modal = ({
             };
         });
 
+        if (timezone !== intialTimezone) {
+            newSchedule.time_zone = timezone;
+        }
+
         onSubmit(newSchedule);
     };