Disable flaky ModelDownloader integration tests. am: 5247b140e9 am: 69131b353c am: afd74bcefa am: 0fdac4f42e

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

Change-Id: I8ce53a5452b75a926e3c8cb6fe620cd4eabc8f94
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>