Revert "AC-6714: Temporary changes to test ES8 module on dev docker images - will revert the change after testing"

This reverts commit fbeb5d7.

Author: faizan-shk

app/code/Magento/CatalogSearch/etc/config.xml

@@ -12,7 +12,6 @@
                 <search_terms>1</search_terms>
             </seo>
             <search>
-                <engine>elasticsearch8</engine>
                 <min_query_length>3</min_query_length>
                 <max_query_length>128</max_query_length>
                 <max_count_cacheable_search_terms>100</max_count_cacheable_search_terms>

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

@@ -9,6 +9,7 @@
     <default>
         <catalog>
             <search>
+                <engine>elasticsearch7</engine>
                 <elasticsearch7_server_hostname>localhost</elasticsearch7_server_hostname>
                 <elasticsearch7_server_port>9200</elasticsearch7_server_port>
                 <elasticsearch7_index_prefix>magento2</elasticsearch7_index_prefix>

app/code/Magento/OpenSearch/etc/config.xml

@@ -9,6 +9,7 @@
     <default>
         <catalog>
             <search>
+                <engine>opensearch</engine>
                 <opensearch_server_hostname>localhost</opensearch_server_hostname>
                 <opensearch_server_port>9200</opensearch_server_port>
                 <opensearch_index_prefix>magento2</opensearch_index_prefix>