Remove Debian10 Flutter_Android, change BuildStats to use Debian9 Docker

Bug: skia:9438
Change-Id: Ieef20c71622d7db4f9be9d54b393eec123b19d8b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/284041
Auto-Submit: Weston Tracey <westont@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
2 files changed