[8.x] [Discover] Fix console warning for invalid DOM property (#204417)…

… (#204605)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[Discover] Fix console warning for invalid DOM property
(#204417)](#204417)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Arturo Castillo
Delgado","email":"[email protected]"},"sourceCommit":{"committedDate":"2024-12-17T15:49:36Z","message":"[Discover]
Fix console warning for invalid DOM property (#204417)\n\nFixes one of
the errors described in #202287 — namely a console warning\r\ndue to
invalid DOM
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Fix console warning for invalid DOM
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Fix console warning for invalid DOM property (#204417)\n\nFixes one of
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Fix console warning for invalid DOM property (#204417)\n\nFixes one of
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BACKPORT-->

Co-authored-by: Arturo Castillo Delgado <[email protected]>

src/plugins/unified_doc_viewer/public/components/doc_viewer_flyout/use_flyout_a11y.tsx

@@ -37,7 +37,7 @@ export const useFlyoutA11y = ({ isXlScreen }: { isXlScreen: boolean }) => {
     a11yProps: {
       ref: setFlyoutEl,
       role: isXlScreen ? 'dialog' : undefined,
-      tabindex: isXlScreen ? 0 : undefined,
+      tabIndex: isXlScreen ? 0 : undefined,
       'aria-describedby': isXlScreen ? descriptionId : undefined,
       'data-no-focus-lock': isXlScreen || undefined,
     },