Speed up the scheduler tests by not checking every test against CLI API and gRPC repos
Summary: We have other test coverage that makes sure that cli and gRPC both can launch runs (plus cli api is no longer the default and will be removed at some point hopefully fairly soon). This diff makes it so that the scheduler tests only run against one external repo, dramatically speeeding up run time.
Test Plan: BK, scheduler tests now run comfortably under 10 minutes
Reviewers: max, alangenfeld
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D4839