Remove extract_mr_diff_commit_deletions FF

Changelog: added

app/services/projects/destroy_service.rb

@@ -139,10 +139,7 @@ module Projects
       destroy_web_hooks!
       destroy_project_bots!
       destroy_ci_records!
-
-      if ::Feature.enabled?(:extract_mr_diff_commit_deletions, default_enabled: :yaml)
-        destroy_mr_diff_commits!
-      end
+      destroy_mr_diff_commits!
 
       # Rails attempts to load all related records into memory before
       # destroying: https://github.com/rails/rails/issues/22510

config/feature_flags/development/extract_mr_diff_commit_deletions.yml

----
-name: extract_mr_diff_commit_deletions
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/75963
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/347073
-milestone: '14.6'
-type: development
-group: group::code review
-default_enabled: false

spec/services/projects/destroy_service_spec.rb

@@ -97,9 +97,13 @@ RSpec.describe Projects::DestroyService, :aggregate_failures do
     end
   end
 
-  shared_examples_for "deleting a project with merge requests" do
+  context "deleting a project with merge requests" do
     let!(:merge_request) { create(:merge_request, source_project: project) }
 
+    before do
+      allow(project).to receive(:destroy!).and_return(true)
+    end
+
     it "deletes merge request and related records" do
       merge_request_diffs = merge_request.merge_request_diffs
       expect(merge_request_diffs.size).to eq(1)
@@ -119,25 +123,6 @@ RSpec.describe Projects::DestroyService, :aggregate_failures do
     destroy_project(project, user, {})
   end
 
-  context "extract_mr_diff_commit_deletions feature flag" do
-    context "with flag enabled" do
-      before do
-        stub_feature_flags(extract_mr_diff_commit_deletions: true)
-        allow(project).to receive(:destroy!).and_return(true)
-      end
-
-      it_behaves_like "deleting a project with merge requests"
-    end
-
-    context "with flag disabled" do
-      before do
-        stub_feature_flags(extract_mr_diff_commit_deletions: false)
-      end
-
-      it_behaves_like "deleting a project with merge requests"
-    end
-  end
-
   context 'with running pipelines' do
     let!(:pipelines)               { create_list(:ci_pipeline, 3, :running, project: project) }
     let(:destroy_pipeline_service) { double('DestroyPipelineService', execute: nil) }