Update Scheduler helm schema to use enum types
Summary:
Depends on D5748
As the title, enumify the helm scheduler values, rather
than relying on a boolean toggle.
Test Plan:
bk/helm lint
integration
Reviewers: nate, catherinewu, alangenfeld
Reviewed By: alangenfeld
Differential Revision: https://dagster.phacility.com/D4920