feat(crons): Default checkin_margin to 1 in frontend (#70448)

This isn't super ideal, but at least fixes a bug

Author: evanpurkhiser

static/app/views/monitors/components/detailsSidebar.tsx

@@ -10,7 +10,6 @@ import {Tooltip} from 'sentry/components/tooltip';
 import {IconCopy} from 'sentry/icons';
 import {t, tn} from 'sentry/locale';
 import {space} from 'sentry/styles/space';
-import {defined} from 'sentry/utils';
 import {getFormattedDate} from 'sentry/utils/dates';
 import useCopyToClipboard from 'sentry/utils/useCopyToClipboard';
 import {DEFAULT_MAX_RUNTIME} from 'sentry/views/monitors/components/monitorForm';
@@ -76,13 +75,11 @@ export default function DetailsSidebar({monitorEnv, monitor}: Props) {
       <Thresholds>
         <MonitorIndicator status="warning" size={12} />
         <Text>
-          {defined(checkin_margin)
-            ? tn(
-                'Check-ins missed after %s min',
-                'Check-ins missed after %s mins',
-                checkin_margin
-              )
-            : t('Check-ins that are missed')}
+          {tn(
+            'Check-ins missed after %s min',
+            'Check-ins missed after %s mins',
+            checkin_margin ?? 1
+          )}
         </Text>
         <MonitorIndicator status="error" size={12} />
         <Text>