Role provider should examine state of ConnectionLimit before applying

### What problem are you facing?

When a provider config contains a directive to set ConnectionLimit, it blindly applies the setting without checking the observed state as it does for Privileges and ConfigurationParameters. This is causing additional traffic to the catalog that is unhelpful in a distributed environment.
### How could Crossplane help solve your problem?

In provider-sql/pkg/controller/postgresql/role/reconciler.go:
```
cl := cr.Spec.ForProvider.ConnectionLimit
if cl != nil && cr.Status.AtProvider.ConnectionLimit != cr.Spec.ForProvider.ConnectionLimit {
if err := c.db.Exec(ctx, xsql.Query{
String: fmt.Sprintf("ALTER ROLE %s CONNECTION LIMIT %d", crn, int64(*cl)),
}); err != nil {
return managed.ExternalUpdate{}, errors.Wrap(err, errUpdateRole)
}
}
```