Revert "Add methods to mark some constraints as optional."

This reverts commit eb72459a.

Reason for revert: The plan is to apply it to jobs by default.

Bug: 236261941
Bug: 299346198
Test: atest FrameworksMockingServicesTests:ConnectivityControllerTest
Test: atest FrameworksMockingServicesTests:FlexibilityControllerTest
Test: atest FrameworksMockingServicesTests:JobStatusTest
Change-Id: Ie9a5643caf6e6b68642580b92b10c05a70bd2998