Stop overriding tracking check in experiment stub

With `gitlab-experiment` 0.5.2 a bug got fixed where stubbing
experiments in tests didn't work. With that fix, we can get rid of
overriding the `should_track?` method to always return true, since
we can now rely on the actual implemention, where it can exclude
actors.

spec/experiments/empty_repo_upload_experiment_spec.rb

@@ -8,6 +8,11 @@ RSpec.describe EmptyRepoUploadExperiment, :experiment do
   let(:project) { create(:project, :repository) }
 
   describe '#track_initial_write' do
+    context 'when experiment is turned on' do
+      before do
+        stub_experiments(empty_repo_upload: :control)
+      end
+
       it "tracks an event for the first commit on a project" do
         expect(subject).to receive(:commit_count_for).with(project, max_count: described_class::INITIAL_COMMIT_COUNT, experiment: 'empty_repo_upload').and_return(1)
 
@@ -24,20 +29,21 @@ RSpec.describe EmptyRepoUploadExperiment, :experiment do
         subject.track_initial_write
       end
 
-    it "doesn't track when we generally shouldn't" do
-      allow(subject).to receive(:should_track?).and_return(false)
+      it "doesn't track if the project is older" do
+        expect(project).to receive(:created_at).and_return(described_class::TRACKING_START_DATE - 1.minute)
 
         expect(subject).not_to receive(:track)
 
         subject.track_initial_write
       end
+    end
 
-    it "doesn't track if the project is older" do
-      expect(project).to receive(:created_at).and_return(described_class::TRACKING_START_DATE - 1.minute)
-
+    context 'when experiment is turned off' do
+      it "doesn't track when we generally shouldn't" do
         expect(subject).not_to receive(:track)
 
         subject.track_initial_write
       end
     end
+  end
 end

spec/experiments/new_project_readme_experiment_spec.rb

@@ -29,6 +29,10 @@ RSpec.describe NewProjectReadmeExperiment, :experiment do
   context "when tracking initial writes" do
     let!(:project) { create(:project, :repository) }
 
+    before do
+      stub_experiments(new_project_readme: :control)
+    end
+
     it "tracks an event for the first commit on a project with a repository" do
       expect(subject).to receive(:commit_count_for).with(project, default_count: described_class::INITIAL_WRITE_LIMIT, max_count: described_class::INITIAL_WRITE_LIMIT, experiment: 'new_project_readme').and_return(1)
       expect(subject).to receive(:track).with(:write, property: project.created_at.to_s, value: 1).and_call_original

spec/support/gitlab_experiment.rb

@@ -12,10 +12,6 @@ class ApplicationExperiment # rubocop:disable Gitlab/NamespacedClass
     super(...)
     Feature.persist_used!(feature_flag_name)
   end
-
-  def should_track?
-    true
-  end
 end
 
 RSpec.configure do |config|