[Stateful:Indices:Pipelines page] Adjustable panels cannot be resized when using screen reader and keyboard only

[L1nBra]

Description
Panels should be adjustable not only when using keyboard, but keyboard and assistive technology as well.

Preconditions
Stateful Indices -> Pipelines page is opened.
Add an inference pipeline step 1, step 2 completed.
Use Screen Reader (NVDA).

Steps to reproduce

1.Navigate to Raw document code editor while using only keyboard by pressing Tab key.
2.Press Tab key.
3.Press left/right arrow key multiple times.
4.Observe screen reader announcement.

NVDA Speech Viewer + UI elements

Actual Result

• Upon reaching the part where user can adjust panels size by pressing left/right arrow key - information about it is announced, but when pressing left/right arrow key size of panels doesn't get adjusted, announcement about "out of button" is made.

Expected Result

• When user presses left/right arrow key - panels sizes are adjusted.

Notes:
Without NVDA it is working correctly.

Meta Issue

Kibana Version: 8.16.0-SNAPSHOT

OS: Windows 11 Pro

Browser: Chrome Version 129.0.6668.101 (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/search-team/issues/8256

[elasticmachine]

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