Describe the bug
pgAdmin users who are authenticated can access each other's directories and files by providing relative paths.

To Reproduce

Steps to reproduce the behavior:

1. Start pgAdmin in the Server mode. You need to create two users 'user1@xyz.com' and 'user2@xyz.com'.
2. Login as user1 and export some servers. Provide the file name as 'servers.json'
3. Login as user2 and Import servers with user2 and set the JSON file name as '../user1_xyz.com/servers.json'.
4. It reads the file and shows the servers to import.

Expected behavior
By providing relative paths, users should not be able to access each other's directories and files.

Desktop (please complete the following information):

• OS: [All]
• Version: [6.18]
• Mode: [Server]