We need to alter the the image sizes that we fetch in the app from:

120, 240, 640, 1280, 2560, 3840 (doubled due to retina devices)

to:

20, 40, 60, 120, 250, 330, 500, 960, 1280, 1920, 3840

Most work was already done for the spike https://phabricator.wikimedia.org/T412161. That work is in the adjust_thumbnails branch. There's only a little bit of cleanup remaining (I would like to remove the LegacyWidth enum entirely and possibly move to a new enum with these 11 sizes). Other than that the plumbing for this is already developed.

Test Steps

In build 7.8.11.

General regression around app images. Confirm that they don't look severely degraded, that the app still scrolls well on lists with lots of thumbnails, that images aren't missing, etc.