[swarming] Disable in-process cache for task_queues.py entities.
[swarming] Disable in-process cache for task_queues.py entities.

It is ndb's on-by-default built-in memory leak essentially. Batteries
included.

Also don't bother with memcache for BotTaskDimensions entity. It is
always read through ndb.Query and mutated via ndb.transaction, as
such it is *never* read through memcache (but transactions still
do useless memcache ops to "flush" it).

(This entity is likely will be gone in future CLs anyway. The same
data should just be represented by a repeated field in BotDimensions
entity).

R=2346c1b958e225fb7eb5e3a6fe644e71150a8db1@google.com, 40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org

Change-Id: Ic7c03768750c49aa1729031fa18fa08dc31d2e91
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/3867936
Commit-Queue: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Reviewed-by: Jonah Hooper <2346c1b958e225fb7eb5e3a6fe644e71150a8db1@google.com>

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