Autofill Fix FillResponse trigger reason

Add cases for
t.metric_array.metric.event.autofill.event_autofill_fill_request_reported.atom.request_trigger_reason:

1. TRIGGER_REASON_EXPLICITLY_REQUESTED (user/app request autofill)
2. TRIGGER_REASON_RETRIGGER (autofill provider trigger autofill)

Test: locally verify logs
Fixes: 326516787
Change-Id: Icdd9c06ced90365d87fa010faa8d6c193fcc8601