Before this CL, output switcher will show 2 media sessions when
some apps are remote playing. The root cause is some apps will
also create local media sessions when they cast media to remote
playing.
This CL add condition to only show remote sessions on output switcher
if apps both have remote and local sessions.
Bug: 169052790
Test: make -j42 RunSettingsRoboTests
Change-Id: I80479d35b2bb2e353cf41f41f457f2dfd15cadbf
e16a8077b5