6296 fix charts and custom retention labels

Updates #6296

Squashed commit of the following:

commit e6a36f107b7bdd17fe4141b035fe5c1f6edd5c6c
Author: Ildar Kamalov <ik@adguard.com>
Date:   Fri Oct 13 17:42:41 2023 +0300

    changelog

commit 96f11f2090d2aff600f6dcd6ca601e25cd857530
Author: Ildar Kamalov <ik@adguard.com>
Date:   Fri Oct 13 16:01:27 2023 +0300

    changelog

commit 136fb14f61dcb2bdec3bc9b8943a05544752a606
Author: Ildar Kamalov <ik@adguard.com>
Date:   Fri Oct 13 15:20:14 2023 +0300

    ADG-7598 fix charts and custom retention labels

client/src/helpers/constants.js

@@ -554,3 +554,8 @@ export const DISABLE_PROTECTION_TIMINGS = {
 };
 
 export const LOCAL_TIMEZONE_VALUE = 'Local';
+
+export const TIME_UNITS = {
+    HOURS: 'hours',
+    DAYS: 'days',
+};