Disable the Now Playing List for players with no active item

If there is some reason we cant determine the current active item in the
now playing list of the player, disable their now playing list. We do
this by only returning a one item now playing list consisting of the
current item.

Bug: 76128322
Test: View the now playing list on a carkit using a player that doesn't
      have an active item (Used VLC for this test)

Change-Id: I52e2f8daead3baf1028b47e1907871b5506de399
(cherry picked from commit 4598dac7)
Merged-In: I52e2f8daead3baf1028b47e1907871b5506de399