role.postgresql: Secret empty when importing existing role

### What problem are you facing?
Secret is empty when Crossplane is taking control over existing role in the database. Expected it to be propagated with values, like when creating a new role or when changing password

DB: `create role example`

```
apiVersion: postgresql.sql.crossplane.io/v1alpha1
kind: Role
metadata:
name: example
spec:
forProvider: {}
providerConfigRef:
name:
writeConnectionSecretToRef:
name: example
namespace: crossplane-system
```

### How could Crossplane help solve your problem?
By publishing secrets more often.

The issue concerns importing an existing PostgreSQL role through the role.postgresql resource and publishing its connection secret. Start by tracing the existing-role import and secret publication paths, then verify that an imported role produces populated secret values like a newly created role or a password change.

Written by the indexing model from the issue text.