Ensure admin auth is properly setup for Azure PostgreSQL Server

Admin login and password are left empty forAzure PostgreSQL Server, this may lead to unauthorized/anonymous access.

In Azure Console -

1. Open the Azure Portal and go to Azure Database for PostgreSQL servers.
2. Choose the PostgreSQL server you wish to edit.
3. Under Authentication, validate Admin username is mentioned.
4. Select save.

In Terraform -

1. In the azurerm_postgresql_configuration resource, set administrator_login and administrator_login_password.

References:
https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/quickstart-create-server-portal
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/postgresql_server