Thumbnail: Automatically delete a thumbnail after updates

closes #98
4 jobs for multiple_thumbnails in 12 minutes and 32 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #284819
amd64 debian
asan-ubsan

00:12:31

passed #284816
amd64 debian
linux

00:09:56

passed #284817
win32
win32

00:11:57

passed #284818
win64
win64

00:11:29