Use existing transcription from transcription server if available

Repeated requests from the server responds in an ALREADY_EXISTS error and does not transcribe the voicemails. In that case we should ask the server if the request is present already on the server, and if so retrieve it.

Bug: 77236260
Test: N/A
PiperOrigin-RevId: 191016332
Change-Id: I605c546a3bec3599c7b162853463ca7e46f63886
3 files changed