Improve the error message when IntentSender started not for result

This makes sure that if the association request callback IntentResult is
accidentally started not for result, the resulting exception is metioning
it explicitly.

Test: Ensure the error message when calling the IntentSender not for result
  explicitly mentions the requirement for the activity to be called for result.
Bug: 30932767
Change-Id: I689e5af45f1178ddda17ec14aae932c51d940db1