Disable flaky ModelDownloader integration tests. am: 5247b140e9 am: 64c179280c

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/libtextclassifier/+/23472318

Change-Id: Ib27620179f1d1a343de54890dd439fd60ff6222c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>