test(timeline): fix flaky timeline test by wating for detail-panel to… (elastic#269814)

## Summary

Fixes flaky cypress test: 

`x-pack/solutions/security/test/security_solution_cypress/cypress/e2e/investigations/timelines/timelines_table.cy.ts`

Closes: elastic#269981

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Reviewers should verify this PR satisfies this list as well.

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support](https://github.com/elastic/kibana/blob/main/src/platform/packages/shared/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
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were updated or added to match the most common scenarios
- [ ] If a plugin configuration key changed, check if it needs to be
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- [ ] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed
- [ ] The PR description includes the appropriate Release Notes section,
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- [ ] ...

Author: jonwalstedt

x-pack/solutions/security/test/security_solution_cypress/cypress/tasks/timeline.ts

@@ -372,8 +372,10 @@ export const saveTimeline = () => {
 
 export const markAsFavorite = () => {
   cy.intercept('PATCH', 'api/timeline/_favorite').as('markedAsFavourite');
+  cy.intercept('GET', '/api/timelines*').as('timelinesRefreshed');
   cy.get(TIMELINE_PANEL).within(() => cy.get(STAR_ICON).click());
   cy.wait('@markedAsFavourite');
+  cy.wait('@timelinesRefreshed');
 };
 
 export const openTimelineDiscoverAddField = () => {