Add aria-label to Custom Instructions textarea in edit details flyout

[Copilot]

The Custom Instructions EuiTextArea in the Agent Builder edit details flyout has no accessible name. Screen readers only announce placeholder text, not the field title — violating WCAG 4.1.2 (Name, Role, Value).

• Added aria-label={flyoutLabels.instructionsTitle} to the EuiTextArea, reusing the existing i18n string already rendered as the visual heading

[infra-vault-gh-plugin-prod]

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

[kibanamachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: 4774020
• Build duration: 67 mins

Failed CI Steps

• FTR Configs #169

Metrics [docs]

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
agentBuilder	1.3MB	1.3MB	+34.0B

History

• 💛 Build #447731 was flaky ea32402

cc @bhavyarm @Copilot

[kibanamachine]

Starting backport for target branches: 9.3, 9.4

https://github.com/elastic/kibana/actions/runs/26513312603

[kibanamachine]

💔 Some backports could not be created

Status	Branch	Result
❌	9.3	Backport failed because of merge conflicts You might need to backport the following PRs to 9.3: - Fix @elastic/eui/require-table-caption lint violations in drilldown manager UI (#271377) - [Synthetics] Wait for active space before fetching cross-space monitor in flyout !! (#270936) - [Scout] Sanitize Buildkite step keys for nested plugin names (#271412) - [Fleet] Normalize endpoint package policy input ids (#271269)
✅	9.4

Note: Successful backport PRs will be merged automatically after passing CI.

Manual backport

To create the backport manually run:

node scripts/backport --pr 271073

Questions ?

Please refer to the Backport tool documentation

[kibanamachine]

Looks like this PR has a backport PR but it still hasn't been merged. Please merge it ASAP to keep the branches relatively in sync.
cc: @bhavyarm