[Security:Rules:Shared Exception Lists]Missing notification announcement for exported exception list

[L1nBra]

Description
Notification which appears on the page for specific action has to be announced for the user, using assistive technology, that user would understand what just happened and that it really happened/or something failed.

Preconditions
Security -> Rules -> Shared Exception Lists page.
Use Screen Reader (VoiceOver).

Steps to reproduce

1.Navigate to menu (three dots) button and press Enter.
2.Navigate to Export exception list and press Enter.
3.Observe page and screen reader.

UI elements + VoiceOver

Actual Result

• Notification appears on the page that Exception list exported, but it is not announced for the user.

Expected Result

• Notification is announced for the user.

Meta Issue

Version: 9.1.0

OS: macOS Sequoia

Browser: Safari Version 18.5

Screen reader: VoiceOver

WCAG or Vendor Guidance (optional)

• Understanding SC 4.1.3: Status Messages (Level AA)(https://www.w3.org/WAI/WCAG22/Understanding/status-messages.html)

Related to: https://github.com/elastic/kibana-team/issues/1773

[elasticmachine]

Pinging @elastic/kibana-accessibility (Project:Accessibility)

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)

[elasticmachine]

Pinging @elastic/security-detection-engine (Team:Detection Engine)