[Request][ESS][8.14] ES|QL Timeline tab enabled by default and moved to GA

[nastasha-solomon]

Addresses #5138 by updating content and screenshots in the "Investigate events in Timeline" page, and other various screenshots throughout the Security docset. Also contributes to #5149.

Preview:

• Investigate events in Timeline - Removed notes in the "Use ES|QL to investigate events" section and refreshed screenshots throughout the page.

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[PhilippeOberti]

Left a few minor comments. I also noticed that in all the screenshot of the Timeline modal, I see the Elastic AI Assistant tab. This should not be visible anymore as the aiAssistantFlyoutMode feature flag has been turned on by default a few days ago (and backported to the 8.14 branch, see here). The AI assisntant is now by default shown in a flyout, and we don't show the tab in Timeline anymore.

[nastasha-solomon]

I also noticed that in all the screenshot of the Timeline modal, I see the Elastic AI Assistant tab. This should not be visible anymore as the aiAssistantFlyoutMode feature flag has been turned on by default a few days ago (and backported to the 8.14 branch, see elastic/kibana#182633). The AI assisntant is now by default shown in a flyout, and we don't show the tab in Timeline anymore.

Thanks for sharing this, @PhilippeOberti. I'm just now finding out about it, so I'll need to make one more update to the screenshots that I refreshed in this PR and the Serverless one.

[PhilippeOberti]

thanks for updating the screenshots, LGTM!

Only the first one (the Query tab showing old flyout) could be updated, but it seems that you guys will do that in a future PR

[benironside]

LGTM!