Fix silence-injection policy skip in VirtualAudioController Unconditionally register mAudioPlaybackDetector in startListening to ensure the deferred silence injection policy update recovers correctly. Conditionally register mAudioRecordingDetector only when configChangedCallback is provided. Bug: 515034370 Bug: 521392631 Test: atest VirtualAudioControllerTest Flag: EXEMPT BUGFIX Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:26bbdd921d94ef850727a699e87e702fdadeac61 Merged-In: I2af61fc32fb2d19e68037fdb8a10a23dc4b37071 Change-Id: I2af61fc32fb2d19e68037fdb8a10a23dc4b37071