Description
When user clicks on run screenshot diagnostics, the resulting flyout gets announced as "you are in a modal dialog..." which doesn't give any context to non-sighted user.

Preconditions
Stack management->Kibana->AlertsandInsights ->Reporting

Steps to reproduce

1. Navigate to stack management->AlertsAndInsights->Reporting
2. Run voiceover
3. Click on run screenshot diagnostics
4. The resulting flyout gets announced as "you are in a modal dialog..." which doesn't give any context to non-sighted user that they are on run screenshot diagnostics panel.

Kibana Version: 8.18.0

OS: OS X

Browser: Chrome latest

WCAG or Vendor Guidance (optional)

• Understanding SC 4.1.2: Name, Role, Value (Level A)(https://www.w3.org/WAI/WCAG22/Understanding/name-role-value.html)

Related to: https://github.com/elastic/kibana-team/issues/1559