Revert "Add missing #isSpeaking to TTS API V2"

This reverts commit 55490349de9fcd0f5969445a56e2f6d1f1019e08.

I will re-submit this commit after TextToSpeechClient#isSpeaking is in the pre-build framework jar.

Change-Id: I3f9fed2ea1c579f953868732e71973296d152e68
4 files changed