Media Picker: Load video thumbnails for large videos

[ashiagr]

Thumbnails for large videos cannot be previewed in the media picker. This is because the app uses Glide to load thumbnails which starts loading the whole video and allocates memory in order to keep it. This leads to OOM when the size is greater than the available memory. The app adds a check for video size (< 10MB) to avoid this OOM.

See PR #14085 for more details.

The goal of this task is to find out a way to load video thumbnails for large videos.

Steps to reproduce the behavior

1. Go to a site with some big videos uploaded
2. Go to My Site/Media
3. Notice the big videos don't show a thumbnail, instead you can see a grey background (in the light mode)