Do not invalidate stream when the secondary outputs are changed.

When a dynamic policy is registered, the secondary outputs may be
changed. Instead of tearing down the tracks, only tracks whose secondary
outputs are changed will be updated with the new secondary outputs.

Bug: 181582467
Test: atest AudioPlaybackCaptureTest audiopolicy_tests
Test: repo steps in the bug
Change-Id: I9a47a0a4b37ad3f4a1d554dd726ebffb27325141