QCamera2: CTS #testVideoSnapshot updates

- This particular CTS test will try to
  start preview again after video snapshot
  and during video recording. A call to
  start preview in this case will omit
  returning error status.
- Sensors that have only fixed AF mode
  are also expected to return sucess
  when AF is triggered.

CRs-Fixed: 494155
Change-Id: Id1bef71633bb08f46f29d82bdd8ffc3b3282cacd
2 files changed