Remove destroy hooks on Patient

The `PatientDeleter` service class has been introduced as the
designated mechanism for deleting patients. This class handles all
the objects related to `Patient`, making these hooks redundant.

Jira-Issue: MAV-7067

Author: alistair-white-horne-tng

app/models/patient.rb

@@ -77,7 +77,7 @@ class Patient < ApplicationRecord
   has_many :consent_notifications
   has_many :consents
   has_many :gillick_assessments
-  has_many :important_notices, dependent: :destroy
+  has_many :important_notices
   has_many :notes
   has_many :notify_log_entries
   has_many :parent_relationships, -> { order(:created_at) }
@@ -498,8 +498,6 @@ class Patient < ApplicationRecord
   after_update :sync_vaccinations_to_nhs_immunisations_api
   after_commit :generate_important_notice_if_needed, on: :update
   after_commit :search_vaccinations_from_nhs_immunisations_api, on: :update
-  before_destroy :destroy_childless_parents
-
   delegate :fhir_record, to: :fhir_mapper
 
   def sessions
@@ -824,17 +822,6 @@ def locations_are_correct_type
     end
   end
 
-  def destroy_childless_parents
-    parents_to_check = parents.to_a # Store parents before destroying relationships
-
-    # Manually destroy the parent_relationships associated with this Child
-    parent_relationships.each(&:destroy)
-
-    parents_to_check.each do |parent|
-      parent.destroy! if parent.parent_relationships.count.zero?
-    end
-  end
-
   def archive_due_to_deceased!
     archive_reasons =
       teams.map do |team|

spec/models/patient_spec.rb

@@ -1446,36 +1446,6 @@
     end
   end
 
-  describe "#destroy_childless_parents" do
-    context "when parent has only one child" do
-      let(:parent) { create(:parent) }
-      let!(:patient) { create(:patient, parents: [parent]) }
-
-      it "destroys the parent when the patient is destroyed" do
-        expect { patient.destroy }.to change(Parent, :count).by(-1)
-      end
-    end
-
-    context "when parent has multiple children" do
-      let(:parent) { create(:parent) }
-      let!(:patient) { create(:patient, parents: [parent]) }
-
-      before { create(:patient, parents: [parent]) }
-
-      it "does not destroy the parent when one patient is destroyed" do
-        expect { patient.destroy }.not_to change(Parent, :count)
-      end
-    end
-
-    context "when patient has multiple parents" do
-      let!(:patient) { create(:patient, parents: create_list(:parent, 2)) }
-
-      it "destroys only the childless parents" do
-        expect { patient.destroy }.to change(Parent, :count).by(-2)
-      end
-    end
-  end
-
   describe "#latest_pds_search_result" do
     subject(:latest_pds_search_result) { patient.latest_pds_search_result }