Dashboard: Improve API service availability
Dashboard: Improve API service availability

This change raises the minimum instances on standby for API requests
from 1 to 10 and reducing the max concurrent requests down to 20 from 80
pending before scaling up. This allows us to have 200 (20 x 10)
concurrent requests pending to handle bursts of activity for perf
sheriffs.

R=abennetts@google.com, ade7e59805b81f027d537665b2c12c1956198b97@chromium.org

Bug: chromium:1036732
Change-Id: Ibf1ebfbabacef034f24ec1daf6995dbf8d801db6
Reviewed-on: https://chromium-review.googlesource.com/c/catapult/+/1980193
Commit-Queue: Dean Berris <34a37f59e4ade3cf49221306f04217acf3e86255@chromium.org>
Commit-Queue: Chenlin Fan <ade7e59805b81f027d537665b2c12c1956198b97@chromium.org>
Auto-Submit: Dean Berris <34a37f59e4ade3cf49221306f04217acf3e86255@chromium.org>
Reviewed-by: Chenlin Fan <ade7e59805b81f027d537665b2c12c1956198b97@chromium.org>

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