[Observability:Annotations page]Missing action when activating buttons on graph

[L1nBra]

Description
Button elements on activating them should do a corresponding, expected action.

Preconditions
Observability -> Annotations page.
Annotations created.
Use Screen Reader (NVDA).

Steps to reproduce

1.Navigate to buttons on annotations graph.
2.Press Enter.
3.Observe page and screen reader.

UI elements + NVDA Speech Viewer

Actual Result

• Element is announced as button. When user press Enter - nothing happens.

Expected Result

• Because there is information when user hovers over the button, it should be present for user either when reaching the button or when pressing Enter on the button.

Notes:
Information present when user hovers the button

Meta Issue

Kibana Version: 8.17.0-SNAPSHOT

OS: Windows 11 Pro

Browser: Chrome Version 131.0.6778.140 (Official Build) (64-bit)

Screen reader: NVDA

WCAG or Vendor Guidance (optional)

• Understanding SC 2.1.1: Keyboard (Level A)(https://www.w3.org/WAI/WCAG22/Understanding/keyboard.html)

Related to: https://github.com/elastic/kibana-team/issues/1254

[elasticmachine]

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