Enable --enable-display-compositor-pixel-dump for the Android platform.

With this CL, https://chromium-review.googlesource.com/c/chromium/src/+/1213864, this flag was enabled for all other platforms, by default. However, there are many failures that occur on Android with that flag, and because of crbug.com/567947, it is very difficult to debug that problem. Once 567947 gets resolved, get the flag enabled for Android tests.

See here for an example of failures:
https://ci.chromium.org/buildbot/tryserver.chromium.android/android_blink_rel/7651