Adjusted precision of refocus test

Bug: 27747093

Relaxed the precision of the new Refocus test a bit more to tolerate
GPU run.

More cleanups
* Avoided sending new picture intent, since CTS runs in StrictMode
 that forbids exposing piture URI.
* Renamed a parameter with a better name
* Comment rewording

Change-Id: I4393f637ac833142a5ad43c7b2b1851cc9394b29
(cherry picked from commit 067aaadc286a91bed1a636d5d24191b71f069cac)
2 files changed