Remove attorney_assignment_to_colocated feature toggle

[lowellrex]

Now that the AMA effective date has passed an all attorneys are drafting decisions for AMA appeals we have enabled the ability for all attorneys to assign admin actions to the VLJ support staff through Caseflow. This ticket exists to remove the attorney_assignment_to_colocated feature toggle that was previously limiting access to this feature.

Acceptance criteria

• Remove the attorney_assignment_to_colocated feature toggle

[lowellrex]

XS.