[Search:AppSearch:Engines:Documents page]Expandable button missing state announcement

[L1nBra]

Description
The change of button state, value should be accordingly announced. Especially when the same button does one action and when clicked again, the opposite action - it should be announced correctly so as not to confuse users, especially, using assistive technologies.

Preconditions
Stateful App Search -> Engines -> Documents page is opened.
Engine is added.
Use Screen Reader (NVDA).

Steps to reproduce

1.Using only keyboard navigate to Show 5 additional fields button by pressing Tab key.
2.Press Enter few times on it.
3.Observe button and screen reader.

UI elements + NVDA Speech Viewer

Actual Result

• Upon navigating to Show 5 additional fields button, it is announced without a state collapsed. When user presses Enter on it, no announcement that it was expanded, button name changes to Hide additional fields.

Expected Result

• When navigating to Show 5 additional fields button - it is announced as collapsed. When pressed - accordingly collapsed/expanded announced.

Meta Issue

Kibana Version: 8.17.0-SNAPSHOT

OS: Windows 11 Pro

Browser: Chrome Version 130.0.6723.70 (Official Build) (64-bit)

Screen reader: NVDA

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/search-team/issues/8256

[elasticmachine]

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