[Android] DisableAnimationsTestRule sets global Android scales in S+

In Android S+, instead of using reflection to access private API
methods, set the animation scales via global settings.

This makes the rule work in Android S+, though it doesn't work in R-,
therefore the previous code is kept for R-.

Bug: 1225707
Change-Id: I188b5b60edcb1c05076f6d9f64932b6eef01cfc2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4334988


Reviewed-by: Jinsuk Kim <jinsukkim@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1120054}