Fix @elastic/eui/icon-accessibility-rules lint violations across data-discovery files (elastic#269040)

Adds `aria-hidden={true}` to 21 decorative `EuiIcon` instances across 14
files owned by `@elastic/kibana-data-discovery`. All icons are purely
decorative—adjacent text already conveys the same information to
assistive technology.

### Changes

- **External link indicators** (`type="link"`) inside `<EuiLink>` with
visible text — `date.tsx`, `date_nanos.tsx`, `histogram.tsx`,
`number.tsx`, `scripting_syntax.tsx`
- **Chevron/arrow icons** inside buttons/links with text labels —
`view_details_popover.tsx`, `delete_data_view_flyout_content.tsx`
- **Status icons** (warning, error) next to descriptive text —
`badge.tsx`, `field_editor.tsx`, `error_callout.tsx`,
`table_cell_value.tsx`
- **Card/decorative icons** where card title provides meaning —
`empty_index_list_prompt.tsx`, `index_header.tsx`
- **Drag handle** (visual-only affordance) — `field_item_button.tsx`

```tsx
// Before
<EuiIcon type="link" />

// After
<EuiIcon type="link" aria-hidden={true} />
```

Closes elastic#269033

> [!WARNING]
>
> <details>
> <summary>Firewall rules blocked me from connecting to one or more
addresses (expand for details)</summary>
>
> #### I tried to connect to the following addresses, but was blocked by
firewall rules:
>
> - `ci-stats.kibana.dev`
> - Triggering command: `/opt/hostedtoolcache/node/24.14.1/x64/bin/node
/opt/hostedtoolcache/node/24.14.1/x64/bin/node
scripts/yarn_install_scripts.js run ldd 0.8.2` (dns block)
> - Triggering command: `/opt/hostedtoolcache/node/24.14.1/x64/bin/node
/opt/hostedtoolcache/node/24.14.1/x64/bin/node scripts/kbn bootstrap`
(dns block)
> - `clients3.google.com`
> - Triggering command:
`/home/REDACTED/work/kibana/kibana/node_modules/@moonrepo/core-linux-x64-gnu/moon
/home/REDACTED/work/kibana/kibana/node_modules/@moonrepo/core-linux-x64-gnu/moon
run :build-webpack ldd 0.8.2` (dns block)
> - `detectportal.firefox.com`
> - Triggering command:
`/home/REDACTED/work/kibana/kibana/node_modules/@moonrepo/core-linux-x64-gnu/moon
/home/REDACTED/work/kibana/kibana/node_modules/@moonrepo/core-linux-x64-gnu/moon
run :build-webpack ldd 0.8.2` (dns block)
> - `google.com`
> - Triggering command:
`/home/REDACTED/work/kibana/kibana/node_modules/@moonrepo/core-linux-x64-gnu/moon
/home/REDACTED/work/kibana/kibana/node_modules/@moonrepo/core-linux-x64-gnu/moon
run :build-webpack ldd 0.8.2` (dns block)
> - `googlechromelabs.github.io`
> - Triggering command: `/opt/hostedtoolcache/node/24.14.1/x64/bin/node
/opt/hostedtoolcache/node/24.14.1/x64/bin/node install.js` (dns block)
>
> If you need me to access, download, or install something from one of
these locations, you can either:
>
> - Configure [Actions setup
steps](https://gh.io/copilot/actions-setup-steps) to set up my
environment, which run before the firewall is enabled
> - Add the appropriate URLs or hosts to the custom allowlist in this
repository's [Copilot coding agent
settings](https://github.com/elastic/kibana/settings/copilot/coding_agent)
(admins only)
>
> </details>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: alexwizp <20072247+alexwizp@users.noreply.github.com>
Co-authored-by: Alexey Antonov <alexwizp@gmail.com>

Author: Copilot

src/platform/packages/shared/kbn-search-response-warnings/src/components/search_response_warnings/badge.tsx

@@ -57,6 +57,7 @@ export const SearchResponseWarningsBadge = (props: Props) => {
         >
           <EuiIcon
             type="warning"
+            aria-hidden={true}
             css={css`
               margin-left: ${euiTheme.size.xxs};
             `}

src/platform/packages/shared/kbn-search-response-warnings/src/components/search_response_warnings/view_details_popover.tsx

@@ -82,7 +82,7 @@ export const ViewDetailsPopover = (props: Props) => {
             data-test-subj="searchResponseWarningsViewDetails"
           >
             <>
-              {viewDetailsLabel} <EuiIcon type="chevronSingleRight" size="s" />
+              {viewDetailsLabel} <EuiIcon type="chevronSingleRight" size="s" aria-hidden={true} />
             </>
           </EuiLink>
         ) : (

src/platform/packages/shared/kbn-unified-field-list/src/components/field_item_button/field_item_button.tsx

@@ -27,7 +27,7 @@ import { FieldIcon, getFieldIconProps, getFieldSearchMatchingHighlight } from '@
 import { useMemoCss } from '@kbn/css-utils/public/use_memo_css';
 import { type FieldListItem, type GetCustomFieldType } from '../../types';
 
-const DRAG_ICON = <EuiIcon type="drag" size="m" />;
+const DRAG_ICON = <EuiIcon type="drag" size="m" aria-hidden={true} />;
 
 /**
  * Props of FieldItemButton component

src/platform/plugins/shared/data_view_field_editor/public/components/field_format_editor/editors/bytes/__snapshots__/bytes.test.tsx.snap

@@ -60,7 +60,7 @@ export class DateFormatEditor extends DefaultFormatEditor<DateFormatEditorFormat
                   defaultMessage="Documentation"
                 />
                 &nbsp;
-                <EuiIcon type="link" />
+                <EuiIcon type="link" aria-hidden={true} />
               </EuiLink>
             </span>
           }

src/platform/plugins/shared/data_view_field_editor/public/components/field_format_editor/editors/date/__snapshots__/date.test.tsx.snap

@@ -59,7 +59,7 @@ export class DateNanosFormatEditor extends DefaultFormatEditor<DateNanosFormatEd
                   defaultMessage="Documentation"
                 />
                 &nbsp;
-                <EuiIcon type="link" />
+                <EuiIcon type="link" aria-hidden={true} />
               </EuiLink>
             </span>
           }

src/platform/plugins/shared/data_view_field_editor/public/components/field_format_editor/editors/date/date.tsx

@@ -84,7 +84,7 @@ export class HistogramFormatEditor extends DefaultFormatEditor<HistogramFormatEd
                   defaultMessage="Documentation"
                 />
                 &nbsp;
-                <EuiIcon type="link" />
+                <EuiIcon type="link" aria-hidden={true} />
               </EuiLink>
             </span>
           }