Update BUS grant cap based on latest data

- Reduce standard BUS grant cap since we are now starting the simulation in 2024 (r.t. 2022)
- Increase the funding cap for the extended BUS based on gov announcement: https://www.gov.uk/government/news/families-business-and-industry-to-get-energy-efficiency-support

simulation/costs.py

@@ -312,7 +312,7 @@ def estimate_boiler_upgrade_scheme_grant(
         return 0
 
     model_population_scale = ENGLAND_WALES_HOUSEHOLD_COUNT_2020 / model.household_count
-    boiler_upgrade_funding_cap_gbp = 450_000_000 / model_population_scale
+    boiler_upgrade_funding_cap_gbp = 250_000_000 / model_population_scale
     if (
         model.boiler_upgrade_scheme_cumulative_spend_gbp
         >= boiler_upgrade_funding_cap_gbp
@@ -345,7 +345,7 @@ def estimate_extended_boiler_upgrade_scheme_grant(
         return 0
 
     model_population_scale = ENGLAND_WALES_HOUSEHOLD_COUNT_2020 / model.household_count
-    boiler_upgrade_funding_cap_gbp = 1_650_000_000 / model_population_scale
+    boiler_upgrade_funding_cap_gbp = 5_400_000_000 / model_population_scale
     if (
         model.boiler_upgrade_scheme_cumulative_spend_gbp
         >= boiler_upgrade_funding_cap_gbp

simulation/tests/test_costs.py

@@ -227,7 +227,7 @@ def test_boiler_upgrade_scheme_grant_is_zero_when_grant_cap_exceeded(
         model_population_scale = (
             ENGLAND_WALES_HOUSEHOLD_COUNT_2020 / model.household_count
         )
-        boiler_upgrade_scheme_budget_scaled = 450_000_000 / model_population_scale
+        boiler_upgrade_scheme_budget_scaled = 250_000_000 / model_population_scale
 
         model.boiler_upgrade_scheme_cumulative_spend_gbp = (
             boiler_upgrade_scheme_budget_scaled * 0.8
@@ -338,7 +338,7 @@ def test_extended_boiler_upgrade_scheme_grant_is_zero_when_grant_cap_exceeded(
         model_population_scale = (
             ENGLAND_WALES_HOUSEHOLD_COUNT_2020 / model.household_count
         )
-        boiler_upgrade_scheme_budget_scaled = 1_650_000_000 / model_population_scale
+        boiler_upgrade_scheme_budget_scaled = 5_400_000_000 / model_population_scale
 
         model.boiler_upgrade_scheme_cumulative_spend_gbp = (
             boiler_upgrade_scheme_budget_scaled * 0.8