Remove PatientSessionStatusConcern

We no longer have a single status for patient sessions and this is no
longer be used so it can be safely removed.

Author: thomasleese

app/models/concerns/patient_session_status_concern.rb

@@ -25,8 +25,6 @@ class PatientSession < ApplicationRecord
   audited associated_with: :patient
   has_associated_audits
 
-  include PatientSessionStatusConcern
-
   belongs_to :patient
   belongs_to :session