Problem

When images are scrolled off screen in, they appear to be 'reloading' if they are scrolled back onto screen again.
Example of this issue (open full screen to see animated gif):

Why this is problematic:

• It gives the wrong impression that more data is being used to fetch the image again
• Wrong impression that the app performance is slow
• Reloading images is visually jarring

Solution
Dbrant's Gerrit patch comment:
Remove default fade-in animation from Fresco drawees.
This makes image loading feel snappier, especially when scrolling RecyclerView items that contain images.
This also adds an explicit opaque placeholder image which uses the correct background color based on designs, while still allowing the background of loaded images to remain white.

Steps to QA

Note: Using a slower connection will help for this test

1. Open the feed
2. Scroll down to view feed content. It is expected that the images in thumbnails and cards will show firstly in gray background color containers until the image loads.
3. Keep scrolling down after images have finished loading in a view
4. Scroll back up. It is expected that the images previously loaded remain shown when scrolled back into view.