Skip Gerrit tests at class level rather than on each test.

This is simpler, since all of the tests need to be skipped anyway.
It also happens to workaround a bug where network unit tests are
sometimes run on M41 even when --network is not specified.

go/chromeos_release_builder/lumpy%20pre-flight%20release-R41-6680.B/builds/155

BUG=chromium:461409
TEST=Confirm network unit tests aren't run with this change on M41
     builder.

Change-Id: Ie29942d17a84da17a2dbf23422c1aaa40064a9b5
Reviewed-on: https://chromium-review.googlesource.com/252784
Reviewed-by: Dharani Govindan <dharani@chromium.org>
Tested-by: David James <davidjames@chromium.org>
1 file changed