refactor: Remove duplicate user index creation (#8662)

Author: cbaker6

spec/DefinedSchemas.spec.js

@@ -554,7 +554,7 @@ describe('DefinedSchemas', () => {
     });
   });
 
-  it('should not delete automatically classes', async () => {
+  it('should not delete classes automatically', async () => {
     await reconfigureServer({
       schema: { definitions: [{ className: '_User' }, { className: 'Test' }] },
     });

src/Controllers/DatabaseController.js

@@ -1716,12 +1716,6 @@ class DatabaseController {
       throw error;
     });
 
-    await this.adapter
-      .ensureIndex('_User', requiredUserFields, ['username'], 'case_insensitive_username', true)
-      .catch(error => {
-        logger.warn('Unable to create case insensitive username index: ', error);
-        throw error;
-      });
     await this.adapter
       .ensureIndex('_User', requiredUserFields, ['username'], 'case_insensitive_username', true)
       .catch(error => {