Fix force-terminating queued runs from graphql
Summary: If the run cancel call succeeds really quickly during force-termination we were failing the terminate graphql call (fairly egregiously). This case is not common, except for the case where you force-terminate a queued run, where the run will be canceled synchronously as part of the terminate graphql call.
Test Plan: BK in new test suite
Reviewers: johann, dish
Reviewed By: johann
Differential Revision: https://dagster.phacility.com/D5702