Use LUP policy date range for lup claims

LUP will extend past ECP, so we can't use the combined end date when
deciding what subjects to show for nqts who haven't entered an itt,
otherwise we render an empty list on the itt subject screen.

app/models/journeys/additional_payments_for_teaching.rb

@@ -58,7 +58,7 @@ def selectable_subject_symbols(journey_session)
               itt_year: journey_session.answers.itt_academic_year
             )
           end.flatten.uniq
-      elsif journey_session.answers.policy_year.in?(EligibilityCheckable::COMBINED_ECP_AND_LUP_POLICY_YEARS_BEFORE_FINAL_YEAR)
+      elsif journey_session.answers.policy_year.in?(Policies::LevellingUpPremiumPayments::POLICY_RANGE)
         # they get the standard, unchanging LUP subject set because they won't have qualified in time for ECP by 2022/2023
         # and they won't have given an ITT year
         Policies::LevellingUpPremiumPayments.fixed_subject_symbols

app/models/policies/levelling_up_premium_payments.rb

@@ -28,6 +28,7 @@ module LevellingUpPremiumPayments
 
     POLICY_START_YEAR = AcademicYear.new(2022).freeze
     POLICY_END_YEAR = AcademicYear.new(2025).freeze
+    POLICY_RANGE = POLICY_START_YEAR..POLICY_END_YEAR
 
     # Percentage of claims to QA
     MIN_QA_THRESHOLD = 10
@@ -131,7 +132,7 @@ def fixed_subject_symbols
     end
 
     def subject_symbols(claim_year:, itt_year:)
-      return [] unless (POLICY_START_YEAR..POLICY_END_YEAR).cover?(claim_year)
+      return [] unless POLICY_RANGE.cover?(claim_year)
 
       previous_five_years = (claim_year - 5)...claim_year