If the Speed Dial contact only has one channel, place the call immediately.

If the disambig dialog would only show one option, just skip the dialog and
place the call directly. Don't save the number as a default entry though
because the contact could potentially change later (become duo reachable, get
another number, ect.)

Bug: 36841782
Test: SpeedDialIntegrationTest
PiperOrigin-RevId: 193555958
Change-Id: Icbb7e876b7a7c5aaa979980249bf074ec1d7a395