[A11y] Violation in the Observability Alerts Section

[cuff-links]

While adding a new a11y test as part of #141266. I skipped the test and reported the a11y violation here.

Stack Trace:

1)    Observability UI
 │       Overview
 │         "before all" hook for "Guided Setup":
 │
 │      Error: a11y report:
 │
 │ VIOLATION
 │   [aria-valid-attr-value]: Ensures all ARIA attributes have valid values
 │     Impact: critical
 │     Help: https://dequeuniversity.com/rules/axe/4.0/aria-valid-attr-value?application=axeAPI
 │     Elements:
 │       - <button tabindex="-1" class="euiButtonIcon euiButtonIcon--text euiButtonIcon--empty euiButtonIcon--xSmall euiAccordion__iconButton euiAccordion__iconButton-isOpen css-1n6daz4-euiAccordion__iconButton-isOpen" type="button" aria-controls="Log Events" aria-expanded="true" aria-labelledby="i36f01db1-3bc7-11ed-95ec-b3626d1cea06">
 │       - <button id="i36f01db1-3bc7-11ed-95ec-b3626d1cea06" class="euiAccordion__button css-l0a2my-euiAccordion__button" aria-controls="Log Events" aria-expanded="true" type="button">
 │       at AccessibilityService.assertValidAxeReport (/Users/cufflinks/Desktop/workspace/kibana/test/accessibility/services/a11y/a11y.ts:76:13)
 │       at AccessibilityService.testAppSnapshot (/Users/cufflinks/Desktop/workspace/kibana/test/accessibility/services/a11y/a11y.ts:49:10)
 │       at processTicksAndRejections (node:internal/process/task_queues:96:5)
 │       at Context.<anonymous> (test/accessibility/apps/observability.ts:30:9)
 │       at Object.apply (/Users/cufflinks/Desktop/workspace/kibana/node_modules/@kbn/test/target_node/src/functional_test_runner/lib/mocha/wrap_function.js:87:16)
 │

[elasticmachine]

Pinging @elastic/kibana-qa (Team:QA)

[elasticmachine]

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