Add 90% downscale factors.

Add 90% downscale factors and revise other downscale factors to align
with performance analysis.

Minor: Make variables public to allow toggles.

Bug: b/182811243
Test: adb shell am compat enable DOWNSCALED <PACKAGE_NAME> &&
      adb shell am compat enable DOWNSCALE_90 <PACKAGE_NAME>
Change-Id: Ie8ed87b5f8ac1ec25545ff0e75fa1aa5fd48e456