Remove Whitehall pact tests

We are no longer using the Whitehall API, so can remove the pact tests.

The equivalent change has been made in Whitehall: alphagov/whitehall#8029

.github/workflows/ci.yml

@@ -102,12 +102,6 @@ jobs:
     with:
       pact_artifact: pacts
 
-  whitehall_pact:
-    needs: generate_pacts
-    uses: alphagov/whitehall/.github/workflows/pact-verify.yml@main
-    with:
-      pact_artifact: pacts
-
   publish_pacts:
     needs:
       - account_api_pact
@@ -119,7 +113,6 @@ jobs:
       - link_checker_api_pact
       - locations_api_pact
       - publishing_api_pact
-      - whitehall_pact
     if: ${{ github.ref == 'refs/heads/main' }}
     runs-on: ubuntu-latest
     steps:

test/support/pact_helper.rb

@@ -6,7 +6,6 @@
 ACCOUNT_API_PORT = 3004
 LINK_CHECKER_API_PORT = 3005
 IMMINENCE_API_PORT = 3006
-WHITEHALL_API_PORT = 3007
 LOCATIONS_API_PORT = 3008
 ASSET_MANAGER_API_PORT = 3009
 EMAIL_ALERT_API_PORT = 3010
@@ -35,10 +34,6 @@ def imminence_api_host
   "http://localhost:#{IMMINENCE_API_PORT}"
 end
 
-def whitehall_api_host
-  "http://localhost:#{WHITEHALL_API_PORT}"
-end
-
 def locations_api_host
   "http://localhost:#{LOCATIONS_API_PORT}"
 end
@@ -88,12 +83,6 @@ def email_alert_api_host
     end
   end
 
-  has_pact_with "Whitehall API" do
-    mock_service :whitehall_api do
-      port WHITEHALL_API_PORT
-    end
-  end
-
   has_pact_with "Locations API" do
     mock_service :locations_api do
       port LOCATIONS_API_PORT