config: limit GL back pressure feature to mainline product

Limit GL back pressure feature in SurfaceFlinger to be enabled
for mainline product only. This feature at present causes janks
when client composition is enabled for many animation use-cases
for other products.

Change-Id: I780aeb75588e22330a18683e6ca19bf2b23be780
CRs-Fixed: 2568437
1 file changed