[config] Bump GAE instance class F2 => F4_1G.
[config] Bump GAE instance class F2 => F4_1G.

Some config validation requests are timing out and
hitting memory limits. This CL should buy us some time.

R=tandrii@chromium.org, 40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org

Change-Id: I41516e725aea54b9dd9cbc09403f8b5743a8fe7a
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/3116554
Reviewed-by: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Commit-Queue: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>

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