swarming: skip all tests in isolate server in python3
swarming: skip all tests in isolate server in python3

I'll fix the tests one by one later.

Bug: 1010816
Change-Id: I3217e86f4cc6d306123f61b07940ae8e696c068a
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/2277547
Auto-Submit: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>
Commit-Queue: Ye Kuang <1cd89f22f3967fc3dcb883b53940be4b98ec483f@google.com>
Reviewed-by: Ye Kuang <1cd89f22f3967fc3dcb883b53940be4b98ec483f@google.com>

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py