ENGCOM-9077: Add missing index on 'cms_block' table. #32973

 - Merge Pull Request #32973 from Wohlie/magento2:performance/index-on-cms-block
 - Merged commits:
   1. 60cfa24
   2. 86450e9

Author: magento-engcom-team

app/code/Magento/Cms/etc/db_schema.xml

@@ -22,6 +22,9 @@
         <constraint xsi:type="primary" referenceId="PRIMARY">
             <column name="block_id"/>
         </constraint>
+        <index referenceId="CMS_BLOCK_IDENTIFIER" indexType="btree">
+            <column name="identifier"/>
+        </index>
         <index referenceId="CMS_BLOCK_TITLE_IDENTIFIER_CONTENT" indexType="fulltext">
             <column name="title"/>
             <column name="identifier"/>

app/code/Magento/Cms/etc/db_schema_whitelist.json

@@ -10,7 +10,8 @@
             "is_active": true
         },
         "index": {
-            "CMS_BLOCK_TITLE_IDENTIFIER_CONTENT": true
+            "CMS_BLOCK_TITLE_IDENTIFIER_CONTENT": true,
+            "CMS_BLOCK_IDENTIFIER": true
         },
         "constraint": {
             "PRIMARY": true