Update frameworks/av OWNERS files

 - The top-level OWNER bug component only lists media,
   and it is unclear who to reach out to
 - Remove services/OWNERS which seems redundant with the
   top-level OWNERS, since every service has its own OWNERS anyway
 - Update main camera OWNERS with new team members

Change-Id: I0902b21c674a9b78478b530f250667d33172ac6c