Revert "[dashboard] Cache ServiceAccountHttp() in memcache."
Revert "[dashboard] Cache ServiceAccountHttp() in memcache."

This reverts commit 015fbdb559053cab0ddde18585f87f700a087e65.

Reason for revert: Does not work. Gives 403 error when trying to access Swarming service.

Original change's description:
> [dashboard] Cache ServiceAccountHttp() in memcache.
> 
> Just prior to the first request, the Http object makes a request to
> https://accounts.google.com/o/oauth2/token to get an oauth token. Cache
> the HTTP object in memcache to reduce the number of extraneous requests.
> 
> Bug: catapult:#4223
> Change-Id: Id87d24358c4d1cd803c31bf8b69258062216038a
> Reviewed-on: https://chromium-review.googlesource.com/924272
> Commit-Queue: David Tu <baa605d781958521249fdcf7bad76b01d943134a@chromium.org>
> Reviewed-by: Annie Sullivan <sullivan@chromium.org>

TBR=baa605d781958521249fdcf7bad76b01d943134a@chromium.org,sullivan@chromium.org,simonhatch@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: catapult:#4223
Change-Id: I5b386f5d72f2da91ff21a67d859f43d07a8c4fc7
Reviewed-on: https://chromium-review.googlesource.com/926061
Reviewed-by: David Tu <baa605d781958521249fdcf7bad76b01d943134a@chromium.org>
Commit-Queue: David Tu <baa605d781958521249fdcf7bad76b01d943134a@chromium.org>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult