MC-31986: Add support for ES 7 to 2.4-develop

- fix search engines sorting issue.

Author: irenelagno

app/code/Magento/Elasticsearch/etc/di.xml

@@ -163,7 +163,7 @@
     <type name="Magento\Search\Model\Adminhtml\System\Config\Source\Engine">
         <arguments>
             <argument name="engines" xsi:type="array">
-                <item name="elasticsearch5" xsi:type="string">Elasticsearch 5.0+ (Deprecated)</item>
+                <item sortOrder="10" name="elasticsearch5" xsi:type="string">Elasticsearch 5.0+ (Deprecated)</item>
             </argument>
         </arguments>
     </type>

app/code/Magento/Elasticsearch6/etc/di.xml

@@ -17,7 +17,7 @@
     <type name="Magento\Search\Model\Adminhtml\System\Config\Source\Engine">
         <arguments>
             <argument name="engines" xsi:type="array">
-                <item name="elasticsearch6" xsi:type="string">Elasticsearch 6.x</item>
+                <item sortOrder="20" name="elasticsearch6" xsi:type="string">Elasticsearch 6.x</item>
             </argument>
         </arguments>
     </type>

app/code/Magento/Elasticsearch7/etc/di.xml

@@ -17,7 +17,7 @@
     <type name="Magento\Search\Model\Adminhtml\System\Config\Source\Engine">
         <arguments>
             <argument name="engines" xsi:type="array">
-                <item name="elasticsearch7" xsi:type="string">Elasticsearch 7.0+</item>
+                <item sortOrder="30" name="elasticsearch7" xsi:type="string">Elasticsearch 7.0+</item>
             </argument>
         </arguments>
     </type>