[Alerting UI] Console error appears when saving changes in Edit Alert flyout

[YulNaumenko]

Kibana version:
master

Describe the bug:
Console error appears when saving changes in Edit Alert flyout

Steps to reproduce:

1. Open Kibana Alerts and Actions
2. Create new Alert
3. Open browser console
4. Click on the new alert title in the table to navigate to Alert Details
5. Click Edit and do some changes - change title or etc.
6. Click Save
7. Observe that error appeared in the console

Expected behavior:
No error in console

Errors in browser console (if relevant):

react_devtools_backend.js:2450 Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function.
    in AlertEdit
    in Suspense
    in Unknown (created by AlertDetails)
    in AlertsContextProvider (created by AlertDetails)

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)