[Cases] Refresh automated screenshot

[lcawl]

elastic/kibana#167651

This PR refreshes the screenshot that is used in https://www.elastic.co/guide/en/security/current/cases-open-manage.html#cases-ui-manage and https://www.elastic.co/guide/en/security/current/cases-overview.html

Preview

• https://security-docs_bk_4613.docs-preview.app.elstc.co/guide/en/security/master/cases-overview.html
• https://security-docs_bk_4613.docs-preview.app.elstc.co/guide/en/security/master/cases-open-manage.html#cases-ui-manage

[github-actions]

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