improve reliability of scheduleList +timezone e2e tests (#5023)

# What this PR does

Related to grafana/irm#99

## Which issue(s) this PR closes

Closes #4991

grafana-plugin/e2e-tests/schedules/schedulesList.test.ts

@@ -27,9 +27,9 @@ test('schedule calendar and list of schedules is correctly displayed', async ({
   await page.waitForTimeout(2000);
 
   // schedules table displays details created schedule
-  const schedulesTable = page.getByTestId('schedules-table');
-  await expect(schedulesTable.getByRole('cell', { name: onCallScheduleName })).toBeVisible();
-  await expect(schedulesTable.getByRole('cell', { name: 'Web' })).toBeVisible();
-  await expect(schedulesTable.getByRole('cell', { name: userName })).toBeVisible();
-  await expect(schedulesTable.getByRole('cell', { name: 'No team' })).toBeVisible();
+  const schedulesTableLastRow = page.getByTestId('schedules-table').getByRole('row').last();
+  await expect(schedulesTableLastRow.getByRole('cell', { name: onCallScheduleName })).toBeVisible();
+  await expect(schedulesTableLastRow.getByRole('cell', { name: 'Web' })).toBeVisible();
+  await expect(schedulesTableLastRow.getByRole('cell', { name: userName })).toBeVisible();
+  await expect(schedulesTableLastRow.getByRole('cell', { name: 'No team' })).toBeVisible();
 });

grafana-plugin/e2e-tests/schedules/timezones.test.ts

@@ -13,14 +13,33 @@ dayjs.extend(utc);
 dayjs.extend(isoWeek);
 
 test.use({ timezoneId: MOSCOW_TIMEZONE }); // GMT+3 the whole year
-const currentUtcTimeHour = dayjs().utc().format('HH');
-const currentUtcDate = dayjs().utc().format('DD MMM');
-const currentMoscowTimeHour = dayjs().utcOffset(180).format('HH');
-const currentMoscowDate = dayjs().utcOffset(180).format('DD MMM');
 
 test('dates in schedule are correct according to selected current timezone', async ({ adminRolePage }) => {
   const { page, userName } = adminRolePage;
 
+  /**
+   * Always set a fixed time of today's date but at 12:00:00 (noon)
+   *
+   * This solves the issue here https://github.com/grafana/oncall/issues/4991
+   * where we would occasionally see this test flake if it srtated and finished at a different hour
+   *
+   * See playwright docs for more details
+   * https://playwright.dev/docs/clock
+   */
+  const fixedDateAtNoon = new Date().setHours(12, 0, 0, 0);
+  await page.clock.setFixedTime(fixedDateAtNoon);
+
+  /**
+   * Use the fixed time for all time calculations + use the same fixed time for both UTC and Moscow time
+   */
+  const fixedDayjs = dayjs(fixedDateAtNoon).utc();
+
+  // Calculate time and date based on the fixed time
+  const currentUtcTimeHour = fixedDayjs.format('HH'); // 12 in this case
+  const currentUtcDate = fixedDayjs.format('DD MMM');
+  const currentMoscowTimeHour = fixedDayjs.utcOffset(180).format('HH'); // Adjust for Moscow time (UTC+3)
+  const currentMoscowDate = fixedDayjs.utcOffset(180).format('DD MMM');
+
   await setTimezoneInProfile(page, MOSCOW_TIMEZONE);
 
   const onCallScheduleName = generateRandomValue();
@@ -36,7 +55,7 @@ test('dates in schedule are correct according to selected current timezone', asy
   // Selected timezone and local time is correctly displayed
   await expect(page.getByText(`Current timezone: GMT, local time: ${currentUtcTimeHour}`)).toBeVisible();
 
-  // // User avatar tooltip shows correct time and timezones
+  // User avatar tooltip shows correct time and timezones
   await page.getByTestId('user-avatar-in-schedule').hover();
   await expect(page.getByTestId('schedule-user-details_your-current-time')).toHaveText(/GMT\+3/);
   await expect(page.getByTestId('schedule-user-details_your-current-time')).toHaveText(