if a sensitive value is settable, we want to set the returned value (#5835) (#11308)

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

.changelog/5835.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+apikeys: fixed a bug where `google_apikeys_key.key_string` was not being set.
+```

google/resource_apikeys_key.go

@@ -318,6 +318,9 @@ func resourceApikeysKeyRead(d *schema.ResourceData, meta interface{}) error {
 	if err = d.Set("restrictions", flattenApikeysKeyRestrictions(res.Restrictions)); err != nil {
 		return fmt.Errorf("error setting restrictions in state: %s", err)
 	}
+	if err = d.Set("key_string", res.KeyString); err != nil {
+		return fmt.Errorf("error setting key_string in state: %s", err)
+	}
 
 	return nil
 }