fix: [Stateful: Home page] Most Ingest your content section buttons h…

…ave duplicated actions on them (elastic#196079)

Closes: elastic#194932

## Summary

User reaches the same button two times when navigating using only
keyboard and it can get confusing. Also for the user using screen reader
it is also confusing if reached element is button or link. Better for
element to get focus only one time when navigating in sequence from one
element to another and for the user only to hear one announcement of the
element, button or link (but not button link).

## What was changed?:

1. Removed extra `EuiLinkTo` wrapper 
2. `EuiButton` was replaced to `EuiButtonTo`

## Screen 

<img width="1792" alt="image"
src="https://github.com/user-attachments/assets/597eb7f0-dd7b-4c14-bccd-d91dc3bdcbcf">

x-pack/plugins/enterprise_search/public/applications/enterprise_search_content/components/shared/ingestion_card/ingestion_card.tsx

@@ -20,7 +20,7 @@ import {
 
 import { i18n } from '@kbn/i18n';
 
-import { EuiLinkTo } from '../../../../shared/react_router_helpers';
+import { EuiButtonTo } from '../../../../shared/react_router_helpers';
 
 interface IngestionCardProps {
   buttonIcon: IconType;
@@ -78,15 +78,25 @@ export const IngestionCard: React.FC<IngestionCardProps> = ({
       }
       footer={
         onClick ? (
-          <EuiButton isDisabled={isDisabled} iconType={buttonIcon} onClick={onClick} fullWidth>
+          <EuiButton
+            data-test-subj="enterpriseSearchIngestionCardButton"
+            isDisabled={isDisabled}
+            iconType={buttonIcon}
+            onClick={onClick}
+            fullWidth
+          >
             {buttonLabel}
           </EuiButton>
         ) : (
-          <EuiLinkTo to={href ?? ''} shouldNotCreateHref>
-            <EuiButton isDisabled={isDisabled} iconType={buttonIcon} fullWidth>
-              {buttonLabel}
-            </EuiButton>
-          </EuiLinkTo>
+          <EuiButtonTo
+            to={href ?? ''}
+            shouldNotCreateHref
+            isDisabled={isDisabled}
+            iconType={buttonIcon}
+            fullWidth
+          >
+            {buttonLabel}
+          </EuiButtonTo>
         )
       }
     />