Add Assert that Timezone is Formatted Properly

The fixture generation of deploy freezes does not guarantee ordering, so
instead we can create a minimal map of the timezones we expect to assert
against.

This also uncovered a small issue where the timezone identifier was
somehow lost. It seems it was not used, but it would still be better to
save it instead of setting it to undefined.

app/assets/javascripts/deploy_freeze/store/mutations.js

@@ -7,7 +7,7 @@ const formatTimezoneName = (freezePeriod, timezoneList) =>
     cron_timezone: {
       formattedTimezone: timezoneList.find((tz) => tz.identifier === freezePeriod.cron_timezone)
         ?.name,
-      identifier: freezePeriod.cronTimezone,
+      identifier: freezePeriod.cron_timezone,
     },
   });
 

spec/frontend/deploy_freeze/store/mutations_spec.js

@@ -27,15 +27,19 @@ describe('Deploy freeze mutations', () => {
 
   describe('RECEIVE_FREEZE_PERIODS_SUCCESS', () => {
     it('should set freeze periods and format timezones from identifiers to names', () => {
-      const timezoneNames = ['Eastern Time (US & Canada)', 'UTC', 'Berlin'];
+      const timezoneNames = {
+        'Europe/Berlin': 'Berlin',
+        'Etc/UTC': 'UTC',
+        'America/New_York': 'Eastern Time (US & Canada)',
+      };
 
       mutations[types.RECEIVE_FREEZE_PERIODS_SUCCESS](stateCopy, freezePeriodsFixture);
 
-      const expectedFreezePeriods = freezePeriodsFixture.map((freezePeriod, index) => ({
+      const expectedFreezePeriods = freezePeriodsFixture.map((freezePeriod) => ({
         ...convertObjectPropsToCamelCase(freezePeriod),
         cronTimezone: {
-          formattedTimezone: timezoneNames[index],
-          identifier: freezePeriod.cronTimezone,
+          formattedTimezone: timezoneNames[freezePeriod.cron_timezone],
+          identifier: freezePeriod.cron_timezone,
         },
       }));