Dashboards: Fix time range bug when use_browser_locale is enabled 2 (#102750)

* revert

* make it work on initial load

* add integration test; cleanup

* fix test

* fix

packages/grafana-data/src/datetime/parser.test.ts

@@ -32,7 +32,7 @@ describe('dateTimeParse', () => {
 
     const date = dateTimeParse('2025-03-12T07:09:37.253Z', { timeZone: 'browser' });
     expect(date.isValid()).toBe(true);
-    expect(date.format()).toEqual('2025-03-12T02:09:37-05:00');
+    expect(date.format()).toEqual('2025-03-12T07:09:37Z');
   });
 
   it('should be able to parse array formats used by calendar', () => {

packages/grafana-data/src/datetime/parser.ts

@@ -53,29 +53,31 @@ export const dateTimeParse: DateTimeParser<DateTimeOptionsWhenParsing> = (value,
 };
 
 const parseString = (value: string, options?: DateTimeOptionsWhenParsing): DateTime => {
-  const parsed = parse(value, options?.roundUp, options?.timeZone, options?.fiscalYearStartMonth);
   if (value.indexOf('now') !== -1) {
     if (!isValid(value)) {
       return dateTime();
     }
 
+    const parsed = parse(value, options?.roundUp, options?.timeZone, options?.fiscalYearStartMonth);
     return parsed || dateTime();
   }
 
-  const timeZone = getTimeZone(options);
+  let timeZone = getTimeZone(options);
+  let format = options?.format ?? systemDateFormats.fullDate;
+  if (value.endsWith('Z')) {
+    // This is a special case when we have an ISO date string
+    // In this case we want to force the format to be ISO and the timeZone to be UTC
+    // This logic is needed for initial load when parsing the URL params
+    format = 'YYYY-MM-DDTHH:mm:ss.SSSZ';
+    timeZone = 'utc';
+  }
+
   const zone = moment.tz.zone(timeZone);
-  const format = options?.format ?? systemDateFormats.fullDate;
 
   if (zone && zone.name) {
     return dateTimeForTimeZone(zone.name, value, format);
   }
 
-  if (format === systemDateFormats.fullDate) {
-    // We use parsed here to handle case when `use_browser_locale` is true
-    // We need to pass the parsed value to handle case when value is an ISO 8601 date string
-    return dateTime(parsed, format);
-  }
-
   switch (lowerCase(timeZone)) {
     case 'utc':
       return toUtc(value, format);