Ensure no unresolved types in the definition files (#6521)

* Ensure no unresolved types in the definition files

* Address feedback and general cleanup

* Move import from @constants/x to @constants where relevant

* Remove unneeded "import as"

app/database/operator/utils/create_test_connection.ts

@@ -1,8 +1,8 @@
 // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
 // See LICENSE.txt for license information.
 
+import {DatabaseType} from '@constants/database';
 import DatabaseManager from '@database/manager';
-import {DatabaseType} from '@typings/database/enums';
 
 export const createTestConnection = async ({databaseName = 'db_name', setActive = false}) => {
     const serverUrl = 'https://appv2.mattermost.com';