These builds are currently the first in front of PRs; one solution is to speed these up by moving the tests out and running them after the artifacts are available (along with all the framework tests).

E.g.:

18 minutes of testing after a 2.1 minute build:
https://ci.chromium.org/ui/p/flutter/builders/try/Linux%20Engine%20Drone/3032751/overview

4minute build with 24 minutes of testing:
https://ci.chromium.org/ui/p/flutter/builders/try/Mac%20Engine%20Drone/1468415/overview