Rework cut-off decisions in cyclic refresh aq mode

This commit removes the cyclic aq mode dependency on
in_static_area and reworks the corresponding cut-off thresholds.
It improves the compression performance of speed -5 by 1.47% in
PSNR and 2.07% in SSIM, and the compression performance of speed
-6 by 3.10% in PSNR and 5.25% in SSIM. Speed wise, about 1% faster
in both settings at high bit-rates.

Change-Id: I1ffc775afdc047964448d9dff5751491ba4ff4a9
Remove unused is_background function

Change-Id: Ia540eac5f066ae95280c2f898370eddf0110c279
Merge "Rework cut-off decisions in cyclic refresh aq mode"
Merge "Remove unused is_background function"