Android: Disable findbugs

Now that we have errorprone enabled by default, we get faster static
analysis with fewer false positives. Findbugs is no longer necessary.

This CL also unblocks upgrading errorprone to 2.1.2. The rest of the
findbugs annotations and gn args will be removed later.

BUG=777511

Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I9c32f3773f44a7c58813c0ef6a35a81dc9818178
Reviewed-on: https://chromium-review.googlesource.com/734220
Reviewed-by: agrieve <agrieve@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Ken Rockot <rockot@chromium.org>
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Egor Pasko <pasko@chromium.org>
Reviewed-by: Andrei Kapishnikov <kapishnikov@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514187}
24 files changed