chore: revert audio_transcription_service temperature change (out of scope)

Whisper temperature tuning belongs with the transcription stack work,
not with WhatsApp call wiring. Restoring develop's value to keep the
PR focused.

enterprise/app/services/messages/audio_transcription_service.rb

@@ -67,9 +67,7 @@ class Messages::AudioTranscriptionService< Llm::LegacyBaseOpenAiService
         parameters: {
           model: WHISPER_MODEL,
           file: file,
-          # 0.0 minimises Whisper's hallucinations on silence / sub-vocal segments —
-          # higher temperatures produce phantom phrases that look like real transcripts.
-          temperature: 0.0
+          temperature: 0.4
         }
       )
       transcribed_text = response['text']