feat(crons): Indicate when a timeout is incomplete

This looks like this when no terminating check-in was sent.

<img alt="clipboard.png" width="1051" src="https://i.imgur.com/JLOpGtB.png" />k

Fixes [NEW-332: If a timeout does NOT have a duration indicate `incomplete`](https://linear.app/getsentry/issue/NEW-332/if-a-timeout-does-not-have-a-duration-indicate-incomplete)

Author: evanpurkhiser

static/app/views/insights/crons/components/monitorCheckIns.tsx

@@ -2,6 +2,7 @@ import {Fragment} from 'react';
 import styled from '@emotion/styled';
 
 import {SectionHeading} from 'sentry/components/charts/styles';
+import {Tag} from 'sentry/components/core/badge/tag';
 import {Tooltip} from 'sentry/components/core/tooltip';
 import {DateTime} from 'sentry/components/dateTime';
 import Duration from 'sentry/components/duration';
@@ -139,7 +140,16 @@ export function MonitorCheckIns({monitor, monitorEnvs}: Props) {
                     </Tooltip>
                   </div>
                 ) : (
-                  emptyCell
+                  <div>
+                    <Tooltip
+                      title={tct(
+                        'An [code:in_progress] check-in was received, but no terminating [code:ok] or [code:failure] check-in was received. Your job may be terminating without reporting to Sentry.',
+                        {code: <code />}
+                      )}
+                    >
+                      <Tag type="error">{t('Incomplete')}</Tag>
+                    </Tooltip>
+                  </div>
                 )}
                 {checkIn.groups && checkIn.groups.length > 0 ? (
                   <IssuesContainer>